Curve guidance method, curve guidance apparatus, electronic apparatus and program stored in the computer-readable recording medium

ABSTRACT

A road curve guidance method is provided. The road curve guidance method includes: obtaining link information corresponding to a road on which a vehicle is being driven; determining a position of the vehicle on a link at a future time point based on the obtained link information; and judging a degree of risk of a curve section in which the vehicle is to be driven after a predetermined time using the determined position and speed of the vehicle at a reference time point.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Korean Patent Application No.10-2015-0127259 filed on Sep. 8, 2015 and Korean Patent Application No.10-2016-0103276 filed on Aug. 12, 2016 with the Korean IntellectualProperty Office, the disclosures of which are entirely incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a curve guidance method, a curveguidance apparatus, an electronic apparatus, and a program stored in anon-transitory computer-readable recording medium, and moreparticularly, to a curve guidance method, a curve guidance apparatus, anelectronic apparatus, and a program stored in a non-transitorycomputer-readable recording medium that guide a degree of risk of acurve section in real time using link information corresponding to aroad.

2. Description of the Related Art

Recently, as the number of moving bodies such as vehicles continuouslyincreases, traffic congestion has become a serious problem, and becausethe amount of moving bodies is more than what the infrastructure of, forexample, roads, can accommodate, problems caused by traffic congestionhave seriously emerged.

In this situation, a navigation apparatus is a system that receivesattention as one of the solutions for traffic congestion. The navigationapparatus receives a navigation message transmitted by a satellite for aglobal positioning system (GPS) to judge a current position of themoving body, matches the current position of the moving body to map datato be displayed on a screen, and also searches for a driving path fromthe current position of the moving body to a destination. Further, thenavigation apparatus allows a user to efficiently use a given roadnetwork by performing guidance so that the user may drive the movingbody along the searched driving path.

Further, navigations using a function of an advanced driver assistancesystem (ADAS) are recently released. Here, the ADAS, which is a functionfor assisting a driver, may include, for example, a lane departurewarning, a front vehicle starting notification, a road curve guidance, afront vehicle collision notification, and the like.

Among these, the road curve guidance is a function of informing thedriver in advance a curve encountered during the driving of the vehicle.In order to perform the above-mentioned curve guidance, according to therelated art, curve sections are selected by a pre-survey and theselected curve sections are added to map data of a map database (DB) insuch a manner that when the vehicle passes through the correspondingpoint, the corresponding curve section has been guided.

However, the pre-survey method had a problem in that it is difficult toadequately respond to a road situation due to a limit that all areas maynot be pre-surveyed, and was likely to provide incorrect information.

Further, since the curve guidance according to the related art merelyguides whether or not the curve section exists, but does not guide adegree of risk in the curve section according to a current speed of thevehicle, there is a problem in that an accident risk in the curvesection is increased or unnecessary curve guidance is performed.

SUMMARY

An aspect of the present invention may provide an adaptive curveguidance method, a curve guidance apparatus, a navigation apparatus, anda program stored in a non-transitory computer-readable recording mediumthat guide a degree of risk of a curve section in which a vehicle is tobe driven after a predetermined time using a current speed of thevehicle and link information corresponding to a road on which thevehicle is to be driven.

An aspect of the present invention may also provide an adaptive curveguidance method, a curve guidance apparatus, and a program stored in acomputer-readable recording medium that perform a safe driving speedguidance in a curve section using a driving speed of a vehicle andpredicted centrifugal force calculated at a point at which the vehicleis to be located in the future.

According to an aspect of the present invention, a road curve guidancemethod may include: obtaining link information corresponding to a roadincluding a plurality of links on which a vehicle is being driven;determining at least one position of the vehicle on at least one of theplurality of links at at least one future time point based on theobtained link information; and judging a degree of risk of a curvesection of the road in which the vehicle is to be driven after apredetermined time using the determined at least one position and aspeed of the vehicle at a reference time point which corresponds to acurrent position of the vehicle.

The determining of the position of the vehicle further includesrespectively determining a plurality of positions of the vehicle on theplurality of links at each of a plurality of future time points, and thejudging of the degree of risk of the curve section includes computingcentrifugal force to be applied to the vehicle in the curve sectionusing the plurality of determined positions and the speed of the vehicleat the reference time point, and judging the degree of risk of the curvesection based on the computed centrifugal force.

The determining of the plurality of positions of the vehicle mayinclude: determining a first position corresponding to a position of thevehicle on a first link of the plurality of links at a first time point,which is after a first time from the reference time point; determining asecond position corresponding to a position of the vehicle on a secondlink of the plurality of links at a second time point, which is after asecond time from the reference time point; and determining a thirdposition corresponding to a position of a point on the first, the secondlink or a third link that is located between the first link and thesecond link, which is positioned farthest from a line segment connectingthe first position and the second position.

The determining of the plurality of positions of the vehicle mayinclude: determining a first position corresponding to a position of thevehicle on a first link of the plurality of links at a first time point,which is after a first time from the reference time point; determining asecond position corresponding to a position of the vehicle on a secondlink of the plurality of links at a second time point, which is after asecond time from the reference time point; and determining a thirdposition corresponding to a position of at least one point on the firstlink, the second link or a third link that is located between the firstlink and the second link, the third position being positioned betweenthe first position and the second position.

The judging of the degree of risk of the curve section may includegenerating a circumscribed circle including the first position, thesecond position, and the third position.

The judging of the degree of risk of the curve section may includecomputing the centrifugal force to be applied to the vehicle using aradius of the generated circumscribed circle and the speed of thevehicle at the reference time point.

In the judging of the degree of risk of the curve section, the degree ofrisk of the curve section in which the vehicle is to be driven may bejudged by comparing the computed centrifugal force with a presetthreshold value.

The preset threshold value may include a first threshold value, which isa judgment reference of a first risk level, and a second thresholdvalue, which is a judgment reference of a second risk level having thedegree of risk higher than that of the first risk level.

The curve guidance method may further include: when the computedcentrifugal force is greater than the first threshold value and issmaller than the second threshold value, providing a first curve sectionguidance representing that the degree of risk of the curve section inwhich the vehicle is to be driven is the first risk level; and when thecomputed centrifugal force is greater than the second threshold value,providing a second curve section guidance representing that the degreeof risk of the curve section in which the vehicle is to be driven is thesecond risk level.

The obtaining of the link information further includes obtaining linkattribute information. The link information and link attributeinformation corresponding to the road on which the vehicle is beingdriven may be obtained from map data, and the link attribute informationmay include at least one of identifier of the road, a start point and anend point of a reference link of a moving direction of the vehicle, aroad number, a road name, a road length, road rank information, roadwidth information, information of the number of lanes of the road, androad slope information.

The curve guidance method may further include: computing a weight foradjusting the first threshold value and the second threshold value basedon the link attribute information; and adjusting the first thresholdvalue and the second threshold value based on the computed weight.

The weight may vary according to the link attribute information.

According to another aspect of the present invention, a curve guidanceapparatus may include: a link information obtaining unit obtaining linkinformation corresponding to a road including a plurality of links onwhich a vehicle is being driven; a speed sensing unit sensing speed ofthe vehicle; a link position determining unit determining at least oneposition of the vehicle on at least one of the plurality of links at atleast one future time point from a reference time point whichcorresponds to a current position of the vehicle based on the obtainedlink information; and a controlling unit judging a degree of risk of acurve section of the road in which the vehicle is to be driven after apredetermined time using the determined at least one position and aspeed of the vehicle at the reference time point.

The link position determining unit may respectively determine aplurality of positions of the vehicle on the plurality of links at eachof a plurality of future time points, and the controlling unit mayinclude a centrifugal force computing unit computing centrifugal forceto be applied to the vehicle in the curve section using the plurality ofdetermined positions and the speed of the vehicle of the reference timepoint; and a degree of risk judging unit judging the degree of risk ofthe curve section based on the computed centrifugal force.

The link position determining unit may include: a first link positiondetermining unit determining a first position corresponding to aposition of the vehicle on a first link of the plurality of links at afirst time point, which is after a first time from the reference timepoint; a second link position determining unit determining a secondposition corresponding to a position of the vehicle on a second link ofthe plurality of links at a second time point, which is after a secondtime from the reference time point; and a third link positiondetermining unit determining a third position corresponding to aposition of a point on the first link, the second link or a third linkthat is located between the first link and the second link, which ispositioned farthest from a line segment connecting the first positionand the second position.

The link position determining unit may include: a first link positiondetermining unit determining a first position corresponding to aposition of the vehicle on a first link of the plurality of links at afirst time point, which is after a first time from the reference timepoint; a second link position determining unit determining a secondposition corresponding to a position of the vehicle on a second link ofthe plurality of links at a second time point, which is after a secondtime from the reference time point; and a third link positiondetermining unit determining a third position corresponding to aposition of at least one point on the first link, the second link or athird link that is located between the first link and the second link,the third position being positioned between the first position and thesecond position.

The controlling unit may include a circumscribed circle generating unitgenerating a circumscribed circle including the first position, thesecond position, and the third position.

The centrifugal force computing unit may compute centrifugal force to beapplied to the vehicle using a radius of the generated circumscribedcircle and the speed of the vehicle at the reference time point.

The degree of risk judging unit may judge the degree of risk of thecurve section in which the vehicle is to be driven by comparing thecomputed centrifugal force with a preset threshold value.

The preset threshold value may include a first threshold value, which isa judgment reference of a first risk level, and a second thresholdvalue, which is a judgment reference of a second risk level having thedegree of risk higher than that of the first risk level.

The controlling unit may further include a guidance informationgenerating unit generating a first curve section guidance representingthat the degree of risk of the curve section in which the vehicle is tobe driven is the first risk level when the computed centrifugal force isgreater than the first threshold value and is smaller than the secondthreshold value, and generating a second curve section guidancerepresenting that the degree of risk of the curve section in which thevehicle is to be driven is the second risk level when the computedcentrifugal force is greater than the second threshold value.

The link information obtaining unit may further obtain link attributeinformation. The link information and link attribute informationcorresponding to the road on which the vehicle is being driven can beobtained from map data, and the link attribute information may includeat least one of identifier of the road, a start point and an end pointof a reference link of a moving direction of the vehicle, a road number,a road name, a road length, road rank information, road widthinformation, information of the number of lanes of the road, and roadslope information.

The controlling unit may further include a weight computing unitcomputing a weight for adjusting the first threshold value and thesecond threshold value based on the link attribute information, andadjusting the first threshold value and the second threshold value basedon the computed weight.

The weight computed by the weight computing unit may vary according tothe link attribute information.

When the vehicle enters the curve section, the first link positiondetermining unit may determine the first position by shortening thefirst time.

According to another aspect of the present invention, an electronicapparatus may include: an output unit outputting information forguidance; a link information obtaining unit obtaining link informationcorresponding to a road on which a vehicle is being driven; a linkposition determining unit determining a position of the vehicle on alink at a future time point; and a controlling unit judging a degree ofrisk of a curve section in which the vehicle is to be driven after apredetermined time using the determined position and a speed of thevehicle at a reference time point, and controlling the output unit so asto output a curve section guidance corresponding to the judged degree ofrisk.

The degree of risk of the curve section may include de a plurality oflevels, and the curve section guidance may include a first curve sectionguidance output by the output unit when the degree of risk of the curvesection in which the vehicle is to be driven is a first risk level, anda second curve section guidance output by the output unit when thedegree of risk of the curve section in which the vehicle is to be drivenis a second risk level.

The output unit may include a display unit having a screen, and thedisplay unit may position and display a curve guidance object on apredetermined area of an augmented reality screen.

According to another aspect of the present invention, a curve guidancemethod may include: measuring a current position and a current movingspeed of an electronic apparatus using a received global positioningsystem (GPS) signal; generating a curve link based on a plurality oflinks corresponding to a road positioned in a moving direction of theelectronic apparatus from the current position; determining at leastthree points where the electronic apparatus would be positioned atfuture time points according to the measured current moving speed fromthe curve link; calculating a radius of a circumscribed circle passingthrough the at least three the determined points; calculatingcentrifugal force to be applied to a vehicle a vehicle that would moveon the circumscribed circle using the calculated radius and the measuredcurrent moving speed; comparing the calculated centrifugal force with apreset threshold value; and outputting guidance on whether or not thevehicle which would move on a curved road positioned on a front sectionat the current moving speed would be dangerous to a user according to acomparison result.

The threshold value may vary according to link attribute informationcorresponding to the road on the front section.

The link attribute information may include at least one of identifier ofthe road, a start point and an end point of a reference link of a movingdirection of the vehicle, a road number, a road name, a road length,road rank information, road width information, information of the numberof lanes of the road, and road slope information.

The preset threshold value may be a threshold value obtained byexperimental data, and include a first threshold value, which is anexperimental value for informing a risk that the vehicle deviates from aroad of a curve section when the vehicle passes through the curvesection, and a second threshold value, which is an experimental valuefor informing a turnover risk of the vehicle that passes through thecurve section, and the outputting of the guidance may include displayingan attention guidance when the centrifugal force is greater than thefirst threshold value and is smaller than the second threshold value,and displaying a warning guidance when the centrifugal force is greaterthan the second threshold value.

According to another aspect of the present invention, a curve guidanceapparatus may include: a speed sensing unit measuring a current positionand current moving speed of an electronic apparatus using a receivedglobal positioning system (GPS) signal; a curve link generating unitconfigured for generating a curve link based on a plurality of linkscorresponding to a road positioned on a front section in a movingdirection of the electronic apparatus from the current position; a linkposition determining unit determining at least three points where theelectronic apparatus would be positioned according to the measuredcurrent moving speed from the curve link; and a controlling unitcalculating a radius of a circumscribed circle passing through the atleast three determined points, calculating centrifugal force to beapplied to a vehicle when the vehicle would move on the circumscribedcircle using the calculated radius and the measured current movingspeed, comparing the calculated centrifugal force with a presetthreshold value, and outputting guidance on whether or not the vehiclewhich would move on a curved road positioned on a front section at thecurrent moving speed would be dangerous to a user according to acomparison result.

The threshold value may vary according to link attribute informationcorresponding to the road on the front section.

The link attribute information may include at least one of identifier ofthe road, a start point and an end point of a reference link of a movingdirection of the vehicle, a road number, a road name, a road length,road rank information, road width information, information of the numberof lanes of the road, and road slope information.

The preset threshold value may be a threshold value obtained byexperimental data, and include a first threshold value, which is anexperimental value for informing a risk that the vehicle deviates from aroad of a curve section when the vehicle passes through the curvesection, and a second threshold value, which is an experimental valuefor informing a turnover risk of the vehicle that passes through thecurve section, and the controlling unit may display an attentionguidance when the centrifugal force is greater than the first thresholdvalue and is smaller than the second threshold value, and display awarning guidance when the centrifugal force is greater than the secondthreshold value.

According to another aspect of the present invention, a curve guidancemethod may include: obtaining link information on a plurality of linkscorresponding to a road on which a vehicle is to be driven; determiningtwo or more future position points respectively on two or more of theplurality of links positioned on a moving direction from a position of avehicle which is currently being driven using the obtained linkinformation; and judging a degree of risk of a curve section of the roadusing the two or more determined points and driving speed information ofthe vehicle.

The curve guidance method may further include: determining a point on alink which is positioned farthest from a line segment connecting the twoor more future position points; and generating a circumscribed circleincluding the determined three or more points, where the judging of thedegree of risk of the curve section includes calculating the degree ofrisk of the curve section using a radius of the generated circumscribedcircle and the driving speed information.

The calculating of the degree of risk may include: calculatingcentrifugal force of the curve section using the radius of thecircumscribed circle and the driving speed; and providing the degree ofrisk of the curve section to a user by comparing the calculatedcentrifugal force with a preset threshold value.

The curve guidance method may further include: determining a thirdpoint, which is a point on a link positioned farthest from a linesegment connecting the two or more future position points; computing anangle formed by the determined third point and the two end points of theline segment connecting the two or more points; and providing the degreeof risk of the curve section to a user by comparing the computed anglewith a preset threshold value.

According to another aspect of the present invention, a non-transitorycomputer readable recording medium may have a program for performing thecurve guidance method recorded thereon.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a curve guidance apparatusaccording to an exemplary embodiment of the present invention;

FIG. 2 is a block diagram specifically illustrating a curve guidanceapparatus according to an exemplary embodiment of the present invention;

FIG. 3 is a block diagram specifically illustrating a controlling unitof a curve guidance apparatus according to another exemplary embodimentof the present invention;

FIG. 4 is a flowchart illustrating a curve guidance method according toan exemplary embodiment of the present invention;

FIG. 5 is a flowchart illustrating a process of computing centrifugalforce for a vehicle according to an exemplary embodiment of the presentinvention;

FIG. 6 is a view illustrating a process of computing centrifugal forcefor a vehicle according to an exemplary embodiment of the presentinvention;

FIG. 7 is a flowchart specifically illustrating a curve guidance methodaccording to an exemplary embodiment of the present invention;

FIGS. 8A to 8C are views illustrating a method for adjusting a thresholdvalue according to an exemplary embodiment of the present invention;

FIG. 9 is a view specifically illustrating a curve guidance methodaccording to another exemplary embodiment of the present invention;

FIG. 10 is a flowchart illustrating a curve guidance method according toanother exemplary embodiment of the present invention;

FIG. 11 is a view illustrating a curve link according to anotherexemplary embodiment of the present invention;

FIGS. 12A and 12B are views illustrating an example of adjusting a firsttime depending on whether or not a vehicle enters a curve section;

FIG. 13 is a block diagram illustrating a controlling unit according toanother exemplary embodiment of the present invention;

FIGS. 14A and 14B are views illustrating a curve direction judgmentmethod according to an exemplary embodiment of the present invention;

FIG. 15 is a block diagram illustrating an electronic apparatusaccording to an exemplary embodiment of the present invention;

FIG. 16 is a view illustrating a system network connected to theelectronic apparatus according to an exemplary embodiment of the presentinvention;

FIGS. 17A and 17B are views illustrating a curve guidance screen of theelectronic apparatus according to an exemplary embodiment of the presentinvention;

FIG. 18 is a flowchart illustrating a curve guidance method of anelectronic apparatus according to an exemplary embodiment of the presentinvention;

FIG. 19 is a view illustrating an implementation form where a camera andan electronic apparatus according to an exemplary embodiment of thepresent invention are separate components;

FIG. 20 is a view illustrating an implementation form where a camera andan electronic apparatus according to an exemplary embodiment of thepresent invention are integral components; and

FIG. 21 is a view illustrating an implementation form using a head-updisplay (HUD) and an electronic apparatus according to an exemplaryembodiment of the present invention.

DETAILED DESCRIPTION

The following description illustrates only a principle of the presentinvention. Therefore, those skilled in the art may implement theprinciple of the present invention and invent various apparatusesincluded in the spirit and scope of the present invention although notclearly described or shown in the present specification. In addition, itis to be understood that all conditional terms and exemplary embodimentsmentioned in the present specification are obviously intended only toallow those skilled in the art to understand a concept of the presentinvention in principle, and the present invention is not limited toexemplary embodiments and states particularly mentioned as such.

Further, it is to be understood that all detailed descriptionsmentioning specific exemplary embodiments of the present invention aswell as principles, aspects, and exemplary embodiments of the presentinvention are intended to include structural and functional equivalencesthereof. Further, it is to be understood that these equivalences includean equivalence that will be developed in the future as well as anequivalence that is currently well-known, that is, all devices inventedso as to perform the same function regardless of a structure.

Therefore, it is to be understood that, for example, a block diagram ofthe present specification shows a conceptual aspect of an illustrativecircuit for embodying a principle of the present invention. Similarly,it is to be understood that all flow charts, state transition views,pseudo-codes, and the like show various processes that may be tangiblyembodied in a computer-readable medium and that are executed bycomputers or processors regardless of whether or not the computers orthe processors are clearly illustrated.

Functions of various devices including processors or functional blocksrepresented as concepts similar to the processors and illustrated in theaccompanying drawings may be provided by hardware having capability toexecute appropriate software as well as dedicated hardware. When thefunctions are provided by the processors, the above-mentioned functionsmay be provided by a single dedicated processor, a single sharedprocessor, or a plurality of individual processors, in which some ofthem may be shared.

In addition, terms mentioned as a processor, a control, or a conceptsimilar to the processor or the control should not be interpreted toexclusively cite hardware having capability to execute software, butshould be interpreted to implicitly include digital signal processor(DSP) hardware and a read only memory (ROM), a random access memory(RAM), and a non-volatile memory for storing software without beinglimited thereto. The above-mentioned terms may also include well-knownother hardware.

In the claims of the present specification, components represented asmeans for performing functions mentioned in a detailed description areintended to include all methods of performing functions including alltypes of software including, for example, a combination of circuitdevices performing these functions, firmware/micro codes, or the like,and are coupled to appropriate circuits for executing the software so asto execute these functions. It is to be understood that since functionsprovided by variously mentioned means are combined with each other andare combined with a scheme demanded by the claims in the presentinvention defined by the claims, any means capable of providing thesefunctions are equivalent to means recognized from the presentspecification.

The above-mentioned objects, features, and advantages will become moreobvious from the following detailed description associated with theaccompanying drawings. Therefore, those skilled in the art to which thepresent invention pertains may easily practice a technical idea of thepresent invention. Further, in describing the present invention, in thecase in which it is judged that a detailed description of a well-knowntechnology associated with the present invention may unnecessarily makethe gist of the present invention unclear, it will be omitted.

Hereinafter, various exemplary embodiments of the present invention willbe described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a curve guidance apparatusaccording to an exemplary embodiment of the present invention. FIG. 2 isa block diagram specifically illustrating a curve guidance apparatusaccording to an exemplary embodiment of the present invention.

Referring to FIGS. 1 and 2, a curve guidance apparatus 10 may includeall or some of a link information obtaining unit 11, a speed sensingunit 12, a link position determining unit 13, and a controlling unit 14.Here, the link position determining unit 13 may include all or some of afirst link position determining unit 13-1, a second link positiondetermining unit 13-2, and a third link position determining unit 13-3.Further, the controlling unit 14 may include all or some of acircumscribed circle generating unit 14-1, a centrifugal force computingunit 14-2, a weight computing unit 14-3, and a degree of risk judgingunit 14-4.

The curve guidance apparatus 10 may obtain link informationcorresponding to a road on which a vehicle is being driven, maydetermine a position of the vehicle on a link after a predetermined timefrom a reference time point, and judge a degree of risk of a curvesection in which the vehicle is to be driven after the predeterminedtime using the determined position and speed of the vehicle at thereference time point. Here, the curve guidance apparatus 10 may beimplemented using software, hardware, or a combination thereof. As anexample, according to the hardware implementation, the curve guidanceapparatus 10 may be implemented using at least one of applicationspecific integrated circuits (ASICs), digital signal processors (DSPs),digital signal processing devices (DSPDs), programmable logic devices(PLDs), field programmable gate arrays (FPGAs), processors, controllers,micro-controllers, micro-processors, and electrical units for performingother functions.

Such the curve guidance apparatus 10 may perform a curve judgment usinglink information corresponding to the road on which the vehicle is beingdriven.

To this end, the link information obtaining unit 11 may obtain the linkinformation corresponding to the road on which the vehicle is beingdriven. Specifically, the link information obtaining unit 11 may obtainthe link information corresponding to the road on which the vehicle isbeing driven and link attribute information for the corresponding linkfrom map data including a plurality of links for representing roadswithin many areas.

Here, the link information obtaining unit 11 may obtain the map datafrom a storing unit 110 of an electronic apparatus 100 in which thecurve guidance apparatus 10 is installed, or may obtain the map data viawired/wireless communications from an external map database (DB) whichis independent from the electronic apparatus 100, or may obtain the mapdata from another electronic apparatus. For example, the linkinformation obtaining unit 11 may obtain the map data from a map dataprovider via a mobile communications network such as a long termevolution (LTE) or a wireless communications network such as a wirelesslocal area network (LAN).

The map data, which is data for representing the current position and amap of a surrounding area, may include the link information forrepresenting the roads within many areas included in the map data.

The link information may include at least one of information of aplurality of links, link attribute information representing an attributevalue for each of the plurality of links, information of a nodeconnecting the links, and attribute information for the node.

The link attribute information may include at least one of identifier ofthe link, information representing whether or not the link is abi-directional link or a uni-directional link, a start point and an endpoint of a reference link of a moving direction of the vehicle, a roadnumber, a road name, a road length, road rank information, road typeinformation, road width information, information of the number of lanesof the road, road slope information, and guidance code information(e.g., information guiding a speed limit, an enforcement point, and thelike) as illustrated in Table 1. Further, the attribute information forthe node may include direction attribute information.

Here, the bi-directional link may mean a link that defines two-ways,that is, a left road and a right road based on a centerline of the roadas one link.

In addition, the slope information of the road corresponding to the linkmay include longitudinal slope information (longitudinal slope)representing a downward angle or an upward angle for a lengthconcatenated on a horizontal line of the road. Here, it may be judgedbased on the longitudinal slope information whether the roadcorresponding to the corresponding link is an uphill road or a downhillroad. As one exemplary embodiment, if the road is the uphill road in themovement direction of the vehicle, the longitudinal slope informationhas a “positive (+)” value, and if the road is the downhill road, thelongitudinal slope information has a “negative (−)” value.

In addition, the slope information of the road corresponding to the linkmay include superelevation information (Cant) representing a gradient ofa width concatenated on the horizontal line of the road. Here, thesuperelevation of the road corresponding to the corresponding link maybe judged based on the superelevation information. That is, thesuperelevation information is information representing whether an end ofan outer lane in a curved portion of the road is designed to be higherthan an inner lane at an angle of some extent. As one exemplaryembodiment, if the slope is increased in an outer direction of the roadat the center of the road, the superelevation information has a“positive (+)” value, and if the slop is decreased, the superelevationinformation has a “negative (−)” value.

TABLE 1 Attribute Description Road ID Identifier for identifying linkLink Directionality Information Information representing whether link isbi-directional or uni-directional Link Start Point Information Linkstart node identifier Link End Point Information Link end nodeidentifier Road No. Road unique number Road Name Road name Road LengthRoad length information Road Rank Information representing rank of road(rank such as highway, general road, etc.) Road Type Type of road (typesuch as general road, elevated road, underground road, etc.) Road WidthInformation Width information of road Information of Number of Number oflanes of road Lanes of Road Road Slope Information Road longitudinalslope information, road superelevation information Guidance CodeInformation Speed limit, enforcement section, driving caution section,accident hazard information

The speed sensing unit 12 may sense speed of a moving body in which thecurve guidance apparatus 10 is installed, for example, a vehicle, abicycle, a person, or the like (hereinafter, collectively refers themoving body as the vehicle for convenience of explanation).

The link position determining unit 13 may determine a position of thevehicle on the link after a predetermined time from the reference timepoint. Such the link position determining unit 13 may include a firstlink position determining unit 13-1 that determines a first positioncorresponding to a position of the vehicle on the link at a first timepoint, which is after a first time from the reference time point, asecond link position determining unit 13-2 that determines a secondposition corresponding to a position of the vehicle on the link at asecond time point, which is after a second time from the reference timepoint, and a third link position determining unit 13-3 that determines athird position corresponding to a position of at least one point on thelink positioned between the first position and the second position.

Here, the third link position determining unit 13-3 may preferablydetermine a position of a point on the link which is positioned farthestfrom a line segment connecting the first position and the secondposition, as the third position. However, the third link positiondetermining unit 13-3 is not limited thereto, but it may determine aposition of a point on the link positioned between the first positionand the second position, as the third position, according to differentembodiments.

In addition, although the example described above describes only a casein which positions of three links are determined in a front link of acurrent time point of the vehicle, the present invention is not limitedthereto. For example, positions of three or more links in which themoving body may be positioned after the predetermined time from thecurrent time point of the moving body may be determined, and a degree ofrisk of a curve section in which the vehicle is to be driven after thepredetermined time may be judged using the determined positions of thelinks.

Meanwhile, the reference time point may be the current, and the firsttime point and the second time point may be future time points after thepredetermined time from the current. In addition, the second time pointmay be a future time point later than the first time point. For example,the first time point may be a time point after 1 second from thereference time point, and the second time point may be a time pointafter 5 seconds from the reference time point.

Meanwhile, the controlling unit 14 may judge the degree of risk of thecurve section in which the vehicle is to be driven after thepredetermined time, using the position determined by the link positiondetermining unit 13 and the current speed of the vehicle at thereference point sensed by the speed sensing unit 12.

In this case, the controlling unit 14 may compute predicted centrifugalforce of a case in which the vehicle is driven at the current drivingspeed in the curve section, may compare the computed predictedcentrifugal force with a predefined threshold value, and may judge adegree of risk of a case in which the vehicle is driven at the currentspeed on a curve road positioned on a front section, depending on thecomparison result.

To this end, the circumscribed circle generating unit 14-1 may generatea circumscribed circle including the first position, the secondposition, and the third position. In addition, the centrifugal forcecomputing unit 14-2 may compute centrifugal force for the circumscribedcircle using a radius of the generated circumscribed circle and thespeed of the vehicle at the reference time point. In addition, thedegree of risk judging unit 14-4 may judge the degree of risk of thecurve section in which the vehicle is to be driven after thepredetermined time by comparing the computed centrifugal force with apreset threshold value. Here, the preset threshold value, which is athreshold value obtained from experimental data through an actual roaddriving test, may include a first threshold value, which is a judgmentreference of a first risk level (a state in which there is risk that thevehicle gets out of the road of the curve section when the vehiclepasses through the curve section), and a second threshold value, whichis a judgment reference of a second risk level (a state in which thereis turnover risk of the vehicle when the vehicle passes through thecurve section) having the degree of risk higher than that of the firstrisk level.

In addition, the controlling unit 14 may include a weight computing unit14-3. The weight computing unit 14-3 may compute a weight for thethreshold value based on at least one of the road rank information, theroad width information, the information of the number of lanes of theroad, and the road slope information of the obtained link information,and may adjust a preset threshold value based on the computed weight.

Hereinafter, two cases in which the weight computing unit 14-3 changesthe weight according to the link attribute information will bedescribed.

<Case 1>

In Case 1, the weight computing unit 14-3 may set the weight to “1” or a“value greater than 1” according to the link attribute information. Forexample, the “value greater than 1” will be a value including decimalplaces that exceed 1 including “1.001”.

In a case in which the number of lanes of the curve section is large,the degree of risk felt by the driver in relation to the curve sectionwill be smaller than a case in which the number of lanes of the curvesection is small. Therefore, in Case 1, when the number of lanes of theroad obtained by the link information obtaining unit 11 is a presetnumber of lanes (one-lane), the weight computing unit 14-3 may computethe weight as a value of ‘1’. In addition, when the number of lanes ofthe road obtained by the link information obtaining unit 11 is greaterthan the preset number of lanes (one-lane), the weight computing unit14-3 may compute the weight as a value greater than ‘1’.

As another example, the weight computing unit 14-3 may further considera weight of 0.1 for each of the exceeded number of lanes whenever thenumber of lanes exceeds one-lane. If the number of lanes is one, theweight computing unit 14-3 may compute “1” as the weight, if the numberof lanes is two that exceeds one-lane by another, the weight computingunit 14-3 may compute “1.1” as the weight, if the number of lanes isthree, the weight computing unit 14-3 may compute “1.2” as the weight,and if the number of lanes is four, the weight computing unit 14-3 maycompute “1.3” as the weight.

As another example, in a case in which the rank of the road to which thecurve section belongs is the highway, the degree of risk felt by thedriver in relation to the curve section will be smaller than the generalroad. Therefore, in a case in which the road rank obtained by the linkinformation obtaining unit 11 is the general road, the weight computingunit 14-3 may compute the weight as ‘1’. In addition, in a case in whichthe road rank obtained by the link information obtaining unit 11 is thehighway, the weight computing unit 14-3 may compute the weight as avalue greater than ‘1’.

As still another example, in a case in which the road width of the curvesection is wide, the degree of risk felt by the driver in relation tothe curve section will be smaller than a case in which the road width ofthe curve section is narrow. Therefore, in a case in which the roadwidth obtained by the link information obtaining unit 11 is the same asa preset value, the weight computing unit 14-3 may compute the weight as‘1’. In addition, in a case in which the road width obtained by the linkinformation obtaining unit 11 is greater than the preset value, theweight computing unit 14-3 may compute the weight as a value greaterthan ‘1’.

As still another example, in a case in which the curve section is on theuphill road, the degree of risk felt by the driver in relation to thecurve section will be smaller than a case in which the curve section ison the downhill road. Therefore, in a case in which the roadlongitudinal slope obtained by the link information obtaining unit 11 isthe uphill road, the weight computing unit 14-3 may compute the weightas a value greater than ‘1’. In addition, in a case in which the roadlongitudinal slope obtained by the link information obtaining unit 11 isthe downhill road, the weight computing unit 14-3 may compute the weightas a value smaller than ‘1’. In addition, in a case in which theobtained road longitudinal slope is a flatland, the weight computingunit 14-3 may not compute the weight or may compute the weight as ‘1’.

As still another example, in a case in which the superelevation of thecurve section is large, the degree of risk felt by the driver inrelation to the curve section will be smaller than a case in which thesuperelevation of the curve section is small. Therefore, in a case inwhich the superelevation of the road obtained by the link informationobtaining unit 11 is greater than a preset value, the weight computingunit 14-3 may compute the weight as the value greater than ‘1’. Inaddition, in a case in which the superelevation of the road obtained bythe link information obtaining unit 11 is smaller than the preset value,the weight computing unit 14-3 may compute the weight as ‘1’.

In addition, in a case in which the superelevation of the road obtainedby the link information obtaining unit 11 is the same as the presetvalue, the weight computing unit 14-3 may compute the weight as ‘1’.Besides, the weight computing unit 14-3 may compute both the weights ofthe flatland and the downhill road as ‘1’.

<Case 2>

In Case 2, the weight computing unit 14-3 may set the weight to “1” or a“value smaller than 1” or a “value greater than 1” according to the linkattribute information. For example, the “value greater than 1” will be avalue including decimal places that exceed 1 including “1.001”, and the“value smaller than 1” may be a value that is more than “0” but lessthan “1”.

As an example, in a case in which the number of lanes of the curvesection is large, the degree of risk felt by the driver in relation tothe curve section will be smaller than a case in which the number oflanes of the curve section is small. Therefore, in Case 2, when thenumber of lanes of the road obtained by the link information obtainingunit 11 is smaller than a preset reference number of lanes (two-lanes),the weight computing unit 14-3 may compute the weight as a value smallerthan “1”. In addition, when the number of lanes of the road obtained bythe link information obtaining unit 11 is greater than the preset numberof lanes, the weight computing unit 14-3 may compute the weight as avalue greater than ‘1’. For example, in a case in which the number oflanes of the obtained link attribute information is one-way, since thenumber of lanes is smaller than the reference number of lanes, theweight computing unit 14-3 may compute the weight as “0.9”, in a case inwhich the number of lanes of the obtained link attribute information isthe reference number of lanes (two-lanes), the weight computing unit14-3 may compute the weight as “1”, and in a case in which the number oflanes of the obtained link attribute information is three-lanes, sincethe number of lanes exceeds the reference number of lanes, the weightcomputing unit 14-3 may compute the weight as “1.1”. As still anotherexample, depending on whether the road width of the curve section issame as a reference road width (e.g., 1.8 m) of the curve section or iswider or narrower than the reference road width thereof, the weightcomputing unit 14-3 may set the weight “1” or the “value smaller than 1”or the “value greater than 1”.

In a case in which the road width of the curve section included in theobtained link attribute information is wide, the degree of risk felt bythe driver in relation to the curve section will be smaller than a casein which the road width of the curve section is narrow. Therefore, theweight computing unit 14-3 may set the weight to “1” or the “valuesmaller than 1” or the “value greater than 1” by comparing the roadwidth obtained by the link information obtaining unit 11 with a presetvalue.

As still another example, in a case in which the curve section is on theuphill road, the degree of risk felt by the driver in relation to thecurve section will be smaller than a case in which the curve section ison the downhill road. Therefore, the weight computing unit 14-3 maycompare the road longitudinal slope information obtained by the linkinformation obtaining unit 11 with reference road longitudinal slopeinformation (e.g., 0 degree) to thereby set the weight to “1” or the“value smaller than 1” or the “value greater than 1” according to thecomparison result.

If the obtained road longitudinal slope information is 0 degree, theweight computing unit 14-3 may assume that the road is a horizontal roadand compute the weight as “1”, if the obtained road longitudinal slopeinformation is 0 degree or more, the weight computing unit 14-3 mayassume that the road is the uphill road, if the obtained roadlongitudinal slope information is more than 0 degree but less than 5degree, the weight computing unit 14-3 may compute the weight as “1.1,and if the obtained road longitudinal slope information is more than 5but less than 10 degrees, the weight computing unit 14-3 may compute theweight as “1.2”.

In contrast, if the obtained road longitudinal slope information has a“negative (−)” value, the weight computing unit 14-3 may assume that theroad is the downhill road, if the obtained road longitudinal slopeinformation is “0 degree to −5 degrees”, the weight computing unit 14-3may compute the weight as “0.9”, and if the obtained road longitudinalslope information is “−5 degree to −10 degrees”, the weight computingunit 14-3 may compute the weight as “0.8”.

As described above, the weight computing method described above may beequally applied to even the case of the superelevation of the road. Thatis, the weight computing unit 14-3 may compare the superelevationinformation with reference road superelevation information (e.g., 0degree) according to the obtained superelevation information of the roadto thereby set the weight to “1” or the “value smaller than 1” or the“value greater than 1” according to the comparison result.

Although the two cases described above describe the examples in whichthe weight computing unit 14-3 computes the weight according to theobtained link attribute information, the weight may also be variedaccording to mass of the vehicle. Since magnitude of the centrifugalforce is increased in proportion to the mass of the vehicle, the degreeof risk felt by the driver of a vehicle having light mass in relation tothe curve section will be relatively smaller than that of a vehiclehaving heavy mass. Therefore, the weight computing unit 14-3 may set theweight to “1” or a “value smaller than 1” or a “value greater than 1”according to the mass of the vehicle.

For example, in a case in which the mass of the vehicle is 2 tons, theweight computing unit 14-3 computes the weight as “1”, whenever the massof the vehicle is increased by 0.5 tons, the weight computing unit 14-3decreases the weight by “0.1”, and whenever the mass of the vehicle isdecreased by 0.5 tons, the weight computing unit 14-3 increases theweight by “0.1”.

Meanwhile, although the example described above describes the case inwhich the weight is computed based on the road attribute informationobtained by the link information obtaining unit 11, the presentinvention is not limited thereto. According to another embodiment of thepresent invention, the curve guidance apparatus 10 may include a sensor(not shown) for sensing at least one of the road rank information, theroad width information, and the information of the number of lanes ofthe road. In this case, the weight computing unit 14-3 may compute theweight for the threshold value based on the road attribute informationobtained by the link information obtaining unit 11 and/or a sensed valueof the sensor (not shown). As an example, the curve guidance apparatus10 may include a sensor (not shown) for measuring a longitudinalgradient and a transverse gradient of the vehicle. In this case, theweight computing unit 14-3 may compute the weight for the thresholdvalue based on a gradient value of the sensor (not shown) for measuringa gradient without the road slope information obtained by the linkinformation obtaining unit 11.

According to the present invention, the threshold value of the guidanceof the degree of risk is adjusted by reflecting factors capable ofinfluencing the degree of risk of the curve section which is felt by asensory organ of the user, for example, the road rank (e.g., whether theroad is the highway or the general road), the road width, the number oflanes of the road (e.g., whether the number of lane of the road is largeor small), the road slope (e.g., whether the road is the uphill road orthe downhill road, thereby making it possible to more accurately performthe guidance for the degree of risk of the curve section. Additionally,as the factor capable of influencing the degree of risk of the curvesection, a kind of pavement of a road surface (e.g., an asphaltpavement, a concrete pavement, etc.) may be considered.

Besides, the weight computing unit 14-3 may also change the weightaccording to information such as a track tread of the vehicle, a widthof the vehicle, a height of the vehicle, a state of a tire, a surfacefriction coefficient, and the like.

FIG. 3 is a block diagram of a controlling unit 14 of a curve guidanceapparatus 10 according to another exemplary embodiment of the presentinvention. In FIG. 3, since the circumscribed circle generating unit14-1 and the centrifugal force computing unit 14-2 are the same as blockconfigurations illustrated in FIG. 2, a description thereof will beomitted. In FIG. 3, a threshold value storing unit 14-5 may pre-storetwo or more threshold values. The threshold values stored in thethreshold value storing unit 14-5 are threshold values obtained asexperimental data through the actual road driving test, and stores afirst threshold value, which is an experimental value for informing(attention) a risk that the vehicle gets out of the road of the curvesection when the vehicle passes through the curve section, and a secondthreshold value, which is an experimental value for informing (warning)a turnover risk of the vehicle that will pass through the curve section.Although another exemplary embodiment of the present invention describesthe two threshold values, it is also possible to predetermine and storethree or more threshold values depending on a selection of a user or amanufacturer.

Of course, it is also possible to preset only one threshold value, andto display information on whether or not the curve section is dangerousdepending on whether or not the threshold value has exceeded.

Meanwhile, in a case in which the computed centrifugal force is smallerthan the first threshold value, since the curve section in which thevehicle is to be driven is not dangerous, a guidance informationgenerating unit 14-6 may not generate curve section guidance.

In addition, in a case in which the computed centrifugal force isgreater than the first threshold value and is smaller than the secondthreshold value, the guidance information generating unit 14-6 maygenerate a first curve section guidance representing that the degree ofrisk of the curve section in which the vehicle is to be driven is thefirst risk level. Here, the first curve section guidance may beattention guidance for informing a risk that the vehicle deviates fromthe road of the curve section when the vehicle passes through the curvesection.

In addition, in a case in which the computed centrifugal force isgreater than the second threshold value, the guidance informationgenerating unit 14-6 may generate a second curve section guidancerepresenting that the degree of risk of the curve section in which thevehicle is to be driven is the second risk level. Here, the second curvesection guidance may be a warning guidance for informing the turnoverrisk of the vehicle that will pass through the curve section.

Meanwhile, the controlling unit 14 may include a curve link generatingunit 14-7 that generates a curve link corresponding to the link using acurve algorithm. Specifically, an actual moving path of the vehicle is acurve, but the links are formed in a straight line. Therefore, in a casein which the positions of the links are determined, or the centrifugalforce is computed by intactly using the prestored links, data to whichactual moving characteristics of the vehicle are reflected is computed,and as a result, accurate guidance of the degree of risk may not beperformed. Therefore, according to an exemplary embodiment of thepresent invention, after obtaining the link information through the linkinformation obtaining unit 11, the curve link generating unit 14-7 maygenerate the curve link corresponding to the link obtained using thecurve algorithm such as a Bezier curve algorithm. In this case, the linkposition determining unit 13 determines a position of the vehicle at afuture time point on the curve link, and the controlling unit 14 judgesthe degree of risk of the curve section in which the vehicle is to bedriven using the position at the future time point determined on thecurve link and the speed of the vehicle at the reference time point,thereby making it possible to more accurately guide the degree of riskof the curve section.

An operation of the curve guidance apparatus 10 of FIGS. 1 and 2 will bedescribed in more detail with reference to FIGS. 4 to 8. The curveguidance apparatus 10 according to the present invention may judge thedegree of risk of the curve section positioned at the front of themoving body as well as provide guidance of speed which is safe fordriving the curve section positioned at the front of the moving body tothe user.

FIG. 4 is a flowchart illustrating a curve guidance method according toan exemplary embodiment of the present invention. Referring to FIG. 4,first, the curve guidance apparatus 10 may obtain link informationcorresponding to a road on which a vehicle is being driven (S101).Specifically, the link information obtaining unit 11 may obtain the linkinformation corresponding to the road on which the vehicle is beingdriven from map data including a plurality of links for representingroads within many areas.

Here, the link information may include the plurality of links andattribute information on each of the plurality of links, information ona node connecting a link and another link, attribute information on thenode, and the like.

In addition, the curve guidance apparatus 10 may determine a position ofthe vehicle on the link at a future time point (S102). A descriptionthereof will be provided in detail with reference to FIGS. 5 and 6.

In addition, the curve guidance apparatus 10 may judge the degree ofrisk of the curve section in which the vehicle is to be driven after apredetermined time when the vehicle drives at current speed, using thedetermined position at the future time point and speed of the vehicle ata reference time point, which is a current position of the vehicle(S103). A description thereof will be provided in detail with referenceto FIG. 7.

FIG. 5 is flowchart illustrating a process of computing centrifugalforce for a vehicle according to an exemplary embodiment of the presentinvention. FIG. 6 is a view illustrating a process of computingcentrifugal force for a vehicle according to an exemplary embodiment ofthe present invention. Referring to FIGS. 5 and 6, first, the linkinformation obtaining unit 11 may obtain link information correspondingto a road on which a vehicle is being driven (S201). As an example, asillustrated in FIG. 6, the link information obtaining unit 11 may obtainthe link information including at least one of a plurality of links 201,202, 203, and 204, nodes 211, 212, 213, and 214 connecting each of theplurality of links 201, 202, 203, and 204 to each other, link attributeinformation on each of the plurality of links, and node attributeinformation.

One link includes a link start node representing a start point of thelink and a link end node representing an end point of the link.

When a vehicle which is not illustrated in FIG. 6 moves on the link 201,the link 202, the link 203, and the link 204 in this order, referencenumeral 211 is the start node of the link of reference numeral 202, andreference numeral 212 is the end node of the link of reference numeral202.

In addition, the link position determining unit 13 may determine acurrent position 221 of an electronic apparatus or the vehicle in whichthe electronic apparatus is installed, using a GPS signal.

In addition, the first link position determining unit 13-1 may determinea first position 222 corresponding to a point at which the vehicle is tobe positioned at a first time point, which is after a first time from areference time point 221, which is the current position of the vehicleon the links 201, 202, 203, and 204 of the vehicle (S202).

In addition, the second link position determining unit 13-2 maydetermine a second position 223 corresponding to a point at which thevehicle is to be positioned at a second time point, which is after asecond time from the reference time point, which is the current positionof the vehicle on the links 201, 202, 203, and 204 of the vehicle(S203).

That is, the first link position determining unit 13-1 and the secondlink position determining unit 13-2 may determine the positioncorresponding to the point at which the vehicle is to be positioned at afuture time point on the links 201, 202, 203, and 204 positioned on amoving direction of the vehicle.

Here, the first and second link position determining units 13-1 and 13-2may compute the first position 222 and the second position 223 using thefollowing Equation 1.

S=V*T  [Equation 1]

V is a speed of the vehicle at the reference time point, T is a time,and S is a moving distance.

In this case, the first link position determining unit 13-1 may computea moving distance after the first time lapses from the current position221 by reflecting current speed of the vehicle and the first time toEquation 1, and may determine the first position 222 based on thecomputed moving distance (S202).

In addition, the second link position determining unit 13-2 may computea moving distance after the second time lapses from the current position221 by reflecting the current speed of the vehicle and the second timeto Equation 1, and may determine the second position 223 based on thecomputed moving distance (S203).

Meanwhile, the third link position determining unit 13-3 may determine athird position 212 corresponding to a position of a point on a linkwhich is positioned farthest from a line segment 231 connecting thefirst position and the second position (S204). In the example of FIG. 6,the third link position determining unit 13-3 may measure aperpendicular line distance 232 from the line segment 231 connecting thefirst position 222 and the second position 223 to a point which existson the links 201, 202, 203, and 204, and may determine a position of thenode 212, which is a position of a point having the longestperpendicular line distance 232 as the third position. Thereafter, thecircumscribed circle generating unit 14-1 may generate a circumscribedcircle 233 including the first position 222, the second position 223,and the third position 212 (S205).

In addition, the centrifugal force computing unit 14-2 may computecentrifugal force for the circumscribed circle using a radius ‘r’ of thegenerated circumscribed circle 233 and the speed of the vehicle at thereference time point (S206). In this case, the centrifugal forcecomputing unit 14-2 may compute the centrifugal force for thecircumscribed circle using the following Equation 2.

$\begin{matrix}{F = {\frac{{mv}^{2}}{r} \times c}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

‘r’ is the radius of the circumscribed circle, ‘m’ is mass of thevehicle, ‘v’ is the speed of the vehicle at the reference time point,‘c’ is a value which is preset according to an experimental value byconsidering various environmental variables such as a road surface state(e.g., a road friction coefficient) of the road, a tire state (e.g., atire friction coefficient), and the like, and F is the magnitude ofcentripetal force. The centrifugal force has the same magnitude as thecentripetal force, but has only a direction opposite to the centrifugalforce.

Here, the mass ‘m’ of the vehicle may be preset as a preset mass valueand may be stored in the storing unit. In addition, ‘c’ may be presetbased on experimental data through the actual road driving test and maybe stored in the storing unit. As still another example, in Equation 2,by considering ‘m’ and ‘c’ as a constant, it is also possible tocalculate F only using values of ‘r’ and ‘v’.

However, according to another implementation, ‘m’ and ‘c’ may be set tovalues which may be changed by an external input. As an example, in acase in which the mass ‘m’ of the vehicle is input through a user input,a pre-stored ‘m’ may be updated to ‘m’ according to the user input. Asanother example, a server may store optimal values of ‘m’ and ‘c’according to a classification reference such as per model, per period,and the like, and the curve guidance apparatus 10 may periodicallycommunicate with the server to receive the values of ‘m’ and ‘c’ tothereby update the pre-stored values of ‘m’ and ‘c’ to the values of ‘m’and ‘c’ received from the server. As still another example, ‘m’ and ‘c’may also be obtained from an electronic control unit (ECU) of thevehicle, and may also be provided from a manufacturer of the vehicle.

Accordingly, in a case in which the vehicle drives at the current speed,the centrifugal force computing unit 14-2 may compute the centrifugalforce to be applied to the vehicle in the curve section in which thevehicle is to be driven after a predetermined time.

Meanwhile, the degree of risk judging unit 14-4 may judge the degree ofrisk of the curve section in which the vehicle is to be driven after thepredetermined time by comparing the computed centrifugal force with apreset threshold value (S207). In this case, the degree of risk judgingunit 14-4 may set a plurality of threshold values and may judge thedegree of risk of the curve section according to situations to therebyprovide the judged degree of risk to a driver. Such a judgment processwill be described in more detail with reference to FIG. 7.

FIG. 7 is a flowchart specifically illustrating a curve guidance methodaccording to an exemplary embodiment of the present invention. Referringto FIG. 7, first, the degree of risk judging unit 14-4 may compare thecentrifugal force computed by the centrifugal force computing unit 14-2with the first threshold value (S301).

If the computed centrifugal force is smaller than the first thresholdvalue (No in S301), the degree of risk judging unit 14-4 may judge thatthe curve section in which the vehicle is to be driven after thepredetermined time is not a dangerous section (S302). As an example, ina case in which the curve section in which the vehicle is to be drivenafter the predetermined time is a curve section having a small degree offlexure (e.g., a section having a large radius of the circumscribedcircle), or in a case in which the current speed of the vehicle is low,the centrifugal force to be applied to the vehicle in the correspondingcurve section may be small. In this case, the degree of risk judgingunit 14-4 may judge that the road on which the vehicle is to be drivenafter the predetermined time is not a dangerous curve section.

If the computed centrifugal force is greater than the first thresholdvalue (Yes in S301), the degree of risk judging unit 14-4 may comparethe computed centrifugal force with the second threshold value (S303).Here, the second threshold value may be a value greater than the firstthreshold value.

If the computed centrifugal force is greater than the first thresholdvalue and is smaller than the second threshold value (No in S303), thedegree of risk judging unit 14-4 may judge the degree of risk of thecurve section in which the vehicle is to be driven after thepredetermined time as a first risk level (S304).

If the computed centrifugal force is greater than the second thresholdvalue (Yes in S303), the degree of risk judging unit 14-4 may judge thedegree of risk of the curve section in which the vehicle is to be drivenafter the predetermined time as a second risk level (S305).

Here, the first risk level may be an attention level informing the userthat an “attention” will be made for the degree of risk of the curvesection of the road on which the vehicle is to be driven, and the secondrisk level may also be a “warning” level at which an attention having alevel higher than the “attention level” is required.

For example, in a case in which the curve section in which the vehicleis to be driven after the predetermined time is a curve section having alarge degree of flexure (e.g., a section having a small radius of thecircumscribed circle), or in a case in which the current speed of thevehicle is high, the magnitude of the centrifugal force to be applied tothe vehicle in the corresponding curve section is measured, such thatinformation such as the “attention” or the “warning” may be provided tothe user according to the measured magnitude before the user enters thecurve section.

In this case, the degree of risk judging unit 14-4 may judge that theroad on which the vehicle is to be driven after the predetermined timeis a curve section that requires the attention or the warning accordingto the comparison between the threshold value and the computedcentrifugal force. Of course, in a case in which the computedcentrifugal force is smaller than the first threshold value, the degreeof risk judging unit 14-4 may judge that a section that the vehiclecurrently enters is a safe section that does not require the attentionor the warning. Of course, even in the safe state, a “safe” indicationrepresenting that the road on which the vehicle is to be driven is thesafe section may also be output to the driver, and in a case in which itis predefined so that only “attention” and “warning” indications areoutput to the driver, the “safe” indication may not also be output.

Meanwhile, the first and second threshold values described above may bechanged based on the link attribute information. Specifically, theweight computing unit 14-3 may compute a weight for the threshold valuebased on at least one of the road rank information, the road widthinformation, the information of the number of lanes of the road, and theroad slope information of the obtained link information, and may adjusta preset threshold value based on the computed weight. A descriptionthereof will be provided in detail with reference to FIG. 8.

FIGS. 8A to 8C are views illustrating an adjustment of a threshold valueaccording to an exemplary embodiment of the present invention. Thedegree of risk of the curve section felt by a sensory organ of the usermay be varied according to the road rank (e.g., the road is the highwayor the general road), the road type, the road width (e.g., informationon whether the road width is wide or narrow, or the road widthinformation), the number of lanes of the road (e.g., information onwhether the number of lane of the road is large or small, or theinformation of the number of lanes of the road), the road slope (e.g.,whether the road is the uphill road or the downhill road, orsuperelevation information), and the like.

As an example, in a case in which the number of lanes of the curvesection is large, the degree of risk felt by the driver in relation tothe curve section will be smaller than a case in which the number oflanes of the curve section is small. In a case in which the number oflanes of the curve section is small, the degree of risk felt by thedriver in relation to the curve section will be greater than a case inwhich the number of lanes of the curve section is large.

As another example, in a case in which the rank of the road to which thecurve section belongs is the highway, the degree of risk felt by thedriver in relation to the curve section will be smaller than the generalroad. In contrast, in a case in which the rank of the road to which thecurve section belongs is the general road, the degree of risk felt bythe driver in relation to the curve section will be greater than thehighway.

As still another example, in a case in which the road width of the curvesection is wide, the degree of risk felt by the driver in relation tothe curve section will be smaller than a case in which the road width ofthe curve section is narrow. In contrast, in a case in which the roadwidth of the curve section is narrow, the degree of risk felt by thedriver in relation to the curve section will be greater than a case inwhich the road width of the curve section is wide.

As still another example, in a case in which the curve section is on theuphill road, the degree of risk felt by the driver in relation to thecurve section will be smaller than a case in which the curve section ison the downhill road. In contrast, in a case in which the curve sectionis on the downhill road, the degree of risk felt by the driver inrelation to the curve section will be greater than a case in which thecurve section is on the uphill road.

As still another example, in a case in which the superelevation of thecurve section is large, the degree of risk felt by the driver inrelation to the curve section will be smaller than a case in which thesuperelevation of the curve section is small. In contrast, in a case inwhich the superelevation of the curve section is small, the degree ofrisk felt by the driver in relation to the curve section will be greaterthan a case in which the superelevation of the curve section is large.

By reflecting the degree of risk felt by the sensory organ of the useraccording to the above-mentioned road attributes, the weight computingunit 14-3 may compute the weight as a value less than ‘1’, ‘1’, or avalue greater than ‘1’, and may adjust a first threshold value (T10) anda second threshold value (T20) based on the computed weight.

According to two cases described above, in Case 1, the weight computingunit 14-3 computes the weight as ‘1’ or the ‘value greater than 1’, andin Case 2, the weight computing unit 14-3 computes the weight as thevalue less than 1′, ‘1’, or the value greater than ‘1’.

Specifically, in a case in which the number of lanes of the curvesection is large, a height of the vehicle is low, mass of the vehicle islight, the width of the vehicle is wide, the rank of the road to whichthe curve section belongs is the highway, the lane width of the curvesection is wide, the curve section is on the uphill road, or thesuperelevation of the curve section is large, the weight computing unit14-3 may compute the weight as the value greater than ‘1’.

In addition, in a case in which the number of lanes of the curve sectionis small, the height of the vehicle is high, the mass of the vehicle isheavy, the width of the vehicle is narrow, the road rank to which thecurve section belongs is the general road, the lane width of the curvesection is narrow, the curve section is on the downhill road, or thesuperelevation of the curve section is small, the weight computing unit14-3 may compute the weight as ‘1’ or the value smaller than ‘1’.

If the respective situations overlap each other, the weight computingunit 14-3 may compute a final weight by multiplying weightscorresponding to the respective situations.

Meanwhile, in a case in which the weight computed by the weightcomputing unit 14-3 is greater than ‘1’, the first threshold value T10and the second threshold value T20 may be adjusted to a 1-2-th thresholdvalue T12 and a 2-2-th threshold value T22, respectively. As such, in acase in which new threshold values become greater than presetthresholds, a degree of risk guidance of the curve section may beperformed in a driving situation (an increase of current driving speed,etc.) in which prediction centrifugal force to be applied to the vehiclebecomes greater than preset centrifugal force (see FIGS. 8A and 8B).

In addition, in a case in which the weight computed by the weightcomputing unit 14-3 is smaller than ‘1’, the first threshold value T10and the second threshold value T20 may be adjusted to a 1-1-th thresholdvalue T11 and a 2-1-th threshold value T21, respectively. As such, in acase in which new threshold values become smaller than the presetthresholds, the degree of risk guidance of the curve section may beperformed even in a driving situation (a decrease of the current drivingspeed, etc.) in which the prediction centrifugal force to be applied tothe vehicle becomes smaller than preset centrifugal force (see FIGS. 8Aand 8C).

Meanwhile, although the exemplary embodiment described above describesthe case in which the weight computing unit 14-3 adjusts the presetthreshold values by applying the weight to the preset threshold valuesbased on at least one of the road rank information, the road typeinformation, the road width information, the road slope information, andthe information of the number of lanes, the present invention is notlimited thereto.

According to another exemplary embodiment of the present invention, theweight computing unit 14-3 may adjust a constant value of m*c bycomputing a second weight for adjusting the constant value of m*cdescribed in Equation 2 based on at least one of the road rankinformation, the road width information, the road slope information, andthe information of the number of lanes, and applying the computed secondweight. As an example, in a case in which the number of lanes of thecurve section is large, the road rank to which the curve section belongsis the highway, the road width of the curve section is wide, the curvesection is on the uphill road, or the superelevation of the curvesection is large, the weight computing unit 14-3 may compute the secondweight as the value smaller than ‘1’. In this case, since thecentrifugal force computed through Equation 2 becomes smaller thancentrifugal force before reflecting the second weight, the degree ofrisk guidance may not be performed even in an existing situation inwhich the degree of risk guidance should be performed.

In addition, in a case in which the number of lanes of the curve sectionis small, the road rank to which the curve section belongs is thegeneral road, the road width of the curve section is narrow, the curvesection is on the downhill road, or the superelevation of the curvesection is small, the weight computing unit 14-3 may compute the secondweight as the value greater than ‘1’. In this case, since thecentrifugal force computed through Equation 2 becomes greater than thecentrifugal force before reflecting the second weight, the degree ofrisk guidance may be performed even in an existing situation in whichthe degree of risk guidance is not performed.

According to various exemplary embodiments of the present invention,since whether or not the road on which the vehicle is to be driven afterthe predetermined time is the curve section may be judged in real timeusing existing retained link information, the curve guidance may beperformed without needing the pre-survey for the curve sections acrossthe country, which incurs high cost.

As well, when the degree of risk for the curve section in which thevehicle is to be driven after the predetermined time is guided, sincethe guidance that a curvature of the curve section and current drivingspeed of the vehicle are simultaneously considered is provided, the usermay more effectively cope with the curve section. As an example, in acase in which because the curvature of the curve section is large, butthe vehicle is currently driven at low speed, the vehicle has lowpossibility that it will be exposed to a risk in the curve section, thedegree of risk is not guided, which prevents the driving of the userfrom being disturbed due to an unnecessary guidance, thereby making itpossible to improve safety of the user.

Further, according to various exemplary embodiments of the presentinvention, the threshold value of the degree of risk guidance isadjusted by reflecting the factors capable of influencing the degree ofrisk of the curve section which is felt by the sensory organ of theuser, for example, the road rank (e.g., the information on whether theroad is the highway or the general road), the road width (e.g.,information on whether the road width is wide or narrow, or the roadwidth information), the number of lanes of the road (e.g., theinformation on whether the number of lane of the road is large or small,or the information of the number of lanes of the road), and the roadslope (e.g., the road longitudinal slope information or thesuperelevation information), thereby making it possible to moreaccurately perform the guidance for the degree of risk of the curvesection. For example, among various exemplary embodiments of the presentinvention, in a case in which the threshold value of the degree of riskguidance is varied according to the road rank, the road rank informationmay be set so as to have a flag value of ‘1’ in the case of the highway,and a flag value of ‘0’ in the case of the general road.

In addition, in a case in which the threshold value of the degree ofrisk guidance is varied according to the road width information, theroad width information may be set to the flag value of ‘0’ and ‘1’ ormay include actual road width information. For example, the road widthinformation may be set so as to have the flag value of ‘1’ in a case inwhich the road width is wide and the flag value of ‘0’ in a case inwhich the road width is narrow, or the road width information may be setso as to have the actual road width information such as ‘1.8 m’.

Further, according various exemplary embodiments of the presentinvention described above, the degree of risk of the curve section isguided being classified into two steps of an ‘attention’ and a‘warning’, thereby making it possible for the user to more effectivelycope with the curve section. Although the present specificationdescribes a case in which the degree of risk is guided being classifiedinto the two steps of the ‘attention’ and the ‘warning’, various guidesaccording to the degree of risk of the curve section may be provided tothe user by classifying the degree of risk into three or more steps.

Meanwhile, according to the example described above, although it isdescribed that the degree of risk judging unit 14-4 judges the degree ofrisk of the curve section in which the vehicle is to be driven after thepredetermined time by comparing the computed centrifugal force with thepreset threshold value, by way of example, the present invention is notlimited thereto. According to another embodiment, the degree of riskjudging unit 14-4 may judge whether or not the road on which the vehicleis to be driven after the predetermined time is a dangerous curvesection when the vehicle is being driven at the current speed, based ona computed flexure angle and the speed of the vehicle at the referencetime point. A description thereof will be provided in detail withreference to FIG. 9.

FIG. 9 is a view specifically illustrating a curve judgment methodaccording to another exemplary embodiment of the present invention. Asillustrated in FIGS. 5 and 6, the first link position determining unit13-1 may determine a first position 322 corresponding to a point atwhich the vehicle is to be positioned at a first time point, which isafter a first time from a reference time point 321 on the links 301,302, 303, and 304 of the vehicle.

In addition, the second link position determining unit 13-2 maydetermine a second position 323 corresponding to a point at which thevehicle is to be positioned at a second time point, which is after asecond time from the reference time point on the links 301, 302, 303,and 304 of the vehicle.

In addition, the third link position determining unit 13-3 may determinea third position corresponding to a position of a point on a link whichis positioned farthest from a line segment 331 connecting the firstposition 322 and the second position 323. In the example of FIG. 9, thethird link position determining unit 13-3 may measure a perpendicularline distance 332 from the line segment 331 connecting the firstposition 322 and the second position 323 to a point which exists on thelinks 301, 302, 303, and 304, and may determine a position of the node312, which is a position of a point having the longest perpendicularline distance 332 as the third position.

In addition, an angle computing unit (not shown) may compute an angle333 formed by an extension line 350 of a line segment 341 connecting thefirst position 322 and the third position 312, and an extension line 360of a line segment 342 connecting the second position 323 and the thirdposition 312.

In this case, the degree of risk judging unit 14-4 may judge the degreeof risk of the curve section in which the vehicle is to be driven afterthe predetermined time by comparing the computed angle 333 with athreshold angle corresponding to the speed of the vehicle at thereference time point. For example, in a case in which the computed angle333 is greater than the threshold angle corresponding to the speed ofthe vehicle at the reference time point, the degree of risk judging unit14-4 may judge that the curve section in which the vehicle is to bedriven after the predetermined time is not dangerous. However, in a casein which the computed angle 333 is smaller than the threshold anglecorresponding to the speed of the vehicle at the reference time point,the degree of risk judging unit 14-4 may judge that the curve section inwhich the vehicle is to be driven after the predetermined time isdangerous.

In this case, the degree of risk judging unit 14-4 may set a pluralityof threshold angles to thereby judge the degree of risk of the curvesection as in the above-mentioned examples. Since these configurationsare apparent based on the above-mentioned examples, a detaileddescription thereof will be omitted.

Meanwhile, the curve guidance apparatus 10 according to an exemplaryembodiment of the present invention may determine the link positionusing the curve link corresponding to the link. A description thereofwill be provided in detail with reference to FIGS. 10 and 11.

FIG. 10 is a flowchart illustrating a curve guidance method according toanother exemplary embodiment of the present invention. FIG. 11 is a viewillustrating a curve link according to another exemplary embodiment ofthe present invention.

Referring to FIGS. 10 and 11, first, the curve guidance apparatus 10 mayobtain link information corresponding to a road on which a vehicle isbeing driven (S401). Specifically, the link information obtaining unit11 may obtain the link information corresponding to the road on whichthe vehicle is being driven from map data including a plurality of linksfor representing roads within many areas.

As an example, as illustrated in FIG. 11, the link information obtainingunit 11 may obtain the link information including at least one of aplurality of links 201, 202, 203, and 204, nodes 211, 212, 213, and 214connecting each of the plurality of links 201, 202, 203, and 204 to eachother, link attribute information on each of the plurality of links, andnode attribute information.

In addition, the curve link generating unit 14-7 may generate the curvelink corresponding to the link obtained using the curve algorithm suchas a Bezier curve algorithm (S402). Specifically, the curve linkgenerating unit 14-7 may generate a curve link 510 corresponding to theplurality of links 201, 202, 203, and 204 using the plurality of links201, 202, 203, and 204, the nodes 211, 212, 213, and 214 connecting eachof the plurality of links 201, 202, 203, and 204 to each other, and aplurality of points included in each of the plurality of links 201, 202,203, and 204.

In addition, the link position determining unit 13 may determine acurrent position 521 on the curve link 510 of an electronic apparatus orthe vehicle in which the electronic apparatus is installed, using a GPSsignal (S403).

In addition, the link position determining unit 13 may determine aposition of the vehicle on the curve link at a future time point (S404).Specifically, the first link position determining unit 13-1 maydetermine a first position 522 corresponding to a point at which thevehicle is to be positioned at a first time point, which is after afirst time from the reference time point on the curve link 510. Inaddition, the second link position determining unit 13-2 may determine asecond position 523 corresponding to a point at which the vehicle is tobe positioned at a second time point, which is after a second time fromthe reference time point on the curve link 510 (S203).

In this case, the first and second link position determining units 13-1and 13-2 may compute the first position 522 and the second position 523using Equation 1 described above.

Meanwhile, the third link position determining unit 13-3 may measure aperpendicular line distance 532 from a line segment 531 connecting thefirst position 522 and the second position 523 to a point which existson the curve link 510, and may determine a position of a point, which isa position of a point having the longest perpendicular line distance 532as the third position 533.

Meanwhile, the degree of risk judging unit 14-4 may judge the degree ofrisk of the curve section in which the vehicle is to be driven using theposition of the vehicle at the future time point determined by the linkposition determining unit 13 and the speed of the vehicle at thereference time point (S405). Specifically, the degree of risk judgingunit 14-4 may compute centrifugal force applied to the vehicle in thecurve section using the plurality of determined positions 522, 523, and533 and the speed of the vehicle at the current time point, which is thereference time point 521, and may judge the degree of risk of the curvesection based on the computed centrifugal force.

According to the present invention described above, the degree of riskof the curve section may be more accurately guided. Specifically, anactual moving path of the vehicle is a curve, but the links are formedin a straight line. Therefore, in a case in which the positions of thelinks are determined, or the centrifugal force is computed by intactlyusing the prestored links, data to which actual moving characteristicsof the vehicle are reflected is computed, and as a result, an accuracyof the degree of risk guidance may be decreased. However, according toan exemplary embodiment of the present invention, the position of thevehicle at the future time point on the curve link is determined, andthe degree of risk of the curve section in which the vehicle is to bedriven is judged using the position of the vehicle at the future timepoint determined on the curve link and the speed of the vehicle at thereference time point, thereby making it possible to more accuratelyguide the degree of risk of the curve section.

Meanwhile, the link position determining unit 13 may determine the firstposition by adjusting the first time depending on whether or not thevehicle enters the curve section. A description thereof will be providedin more detail with reference to FIGS. 12A and 12B.

FIG. 12A is a view illustrating a possible problem that may occur when afirst time is not adjusted depending on whether or not a vehicle entersa curve section. Referring to FIG. 12A, a current position 411 of thevehicle may be close to a curve end point 404 according to a driving ofthe vehicle. In this situation, in a case in which the link positiondetermining unit 13 predicts future positions 412 and 413 of the vehicleusing a first time and a second time which are preset, the futurepositions 412 and 413 may be positioned on links 402 and 403corresponding to a straight line section out of the curve section. Inthis case, since centrifugal force in the corresponding straight linesection is close to zero, the degree of risk judging unit 14-4 may judgethat the degree of risk does not exist in the curve section in which thevehicle is to be driven after the predetermined time, and may end curvesection guidance.

As a result, this may cause a problem that even if the vehicle is beingcurrently driven in the curve section, the curve section guidance ends,by which a driving assistance function for a driver may not beaccurately performed.

FIG. 12B is a view illustrating an example of adjusting a first timedepending on whether or not a vehicle enters a curve section. Referringto FIG. 12B, in a case in which the vehicle enters the curve section anddrives therein, the link position determining unit 13 may determine thefirst position 432 by shortening the first time which is preset. As anexample, in a case in which the first time which is preset is 1 second,when the vehicle enters the curve section, the link position determiningunit 13 may determine the first position 432 by gradually shortening thefirst time such as 0.8 seconds, 0.6 seconds, and 0.4 seconds. In thiscase, a distance difference between the current position 431 of thevehicle and the first position 432, which is a position after the firsttime, may be decreased. That is, in the case in which the vehicle isbeing driven in the curve section, the first position 432 may also bepositioned on the link 421 corresponding to the curve section.

In this case, since the first position 432 is not positioned on thelinks 422 and 423 corresponding to the straight line section, acircumscribed circle 441 having a predetermined radius and including thefirst position 432, the second position 433, and the third position 424may be formed. In addition, the degree of risk judging unit 14-4 mayjudge the degree of risk of the curve section in which the vehicle is tobe driven after the predetermined time based on the current speed of thevehicle.

According to the exemplary embodiment, the problem that the curvesection guidance ends before the vehicle passes through a curve endpoint (in FIG. 12B, the third position 424 corresponds to the curve endpoint) may be solved. Meanwhile, in a case in which the vehicle passesthrough the curve end point 424, the link position determining unit 13-1may determine the first position by adjusting the first time to anoriginal default value.

Meanwhile, the curve guidance apparatus 10 according to anotherexemplary embodiment of the present invention may judge a curvedirection. A description thereof will be provided in detail withreference to FIGS. 13 and 14. Referring to FIG. 13, the curve guidanceapparatus 10 according to another exemplary embodiment of the presentinvention may include a curve direction judging unit 14-8.

Here, the curve direction judging unit 14-8 may judge whether the curvesection in which the vehicle is to be driven after the predeterminedtime is a left curve or a right curve. More specifically, the curvedirection judging unit 14-8 may determine two or more positions of thevehicle on the link at the future time point, may compute vectorsdirected from the current position of the vehicle toward the two or moredetermined positions, and may judge whether the curve section in whichthe vehicle is to be driven after the predetermined time is the leftcurve or the right curve using direction components of an outer productof the computed vectors. A description thereof will be provided in moredetail with reference to FIG. 14.

FIGS. 14A and 14B are views illustrating a curve direction judgmentmethod according to an exemplary embodiment of the present invention.Referring to FIG. 14A, the first link position determining unit 13-1 maydetermine a first position 622 corresponding to a point at which thevehicle is to be positioned at a first time point, which is after afirst time from a current position 621 of the vehicle on the links 601,602, 603, and 604 of the vehicle.

In addition, the second link position determining unit 13-2 maydetermine a second position 623 corresponding to a point at which thevehicle is to be positioned at a second time point, which is after asecond time from the current position 621 of the vehicle on the links601, 602, 603, and 604 of the vehicle.

In this case, the curve direction judging unit 14-8 may compute a firstvector ({right arrow over (v)}₁) 631 directed from the current position621 of the vehicle to the first position 622, and may compute a secondvector ({right arrow over (v)}₂) 632 directed from the current position621 of the vehicle to the second position 623. In addition, the curvedirection judging unit 14-8 may perform the outer product of the firstvector 631 and the second vector 632 to thereby compute directioncomponents. As an example, as illustrated in FIG. 14A, in a case inwhich the first vector 631 and the second vector 632 exist on X and Yaxes, when the outer product of the first vector 631 and the secondvector 632 is performed (Equation: First vector 631×Second vector 632),a direction of the outer product may be a direction of −Z which isperpendicular to the first vector 631 and the second vector 632according to the right-hand law. In this case, the curve directionjudging unit 14-8 may judge the curve section in which the vehicle is tobe driven after the predetermined time as the right curve.

However, as illustrated in FIG. 14B, in a case in which the first vector631 and the second vector 632 are implemented to be bilaterallysymmetrical with FIG. 14A, when the outer product of the first vector631 and the second vector 632 is performed (Equation: First vector631×Second vector 632), the direction of the outer product may be adirection of +Z which is perpendicular to the first vector 631 and thesecond vector 632 according to the right-hand law. In this case, thecurve direction judging unit 14-8 may judge the curve section in whichthe vehicle is to be driven after the predetermined time as the leftcurve.

Further, the curve guidance apparatus 10 may be implemented as onemodule of the electronic apparatus 100 to perform a curve guidancefunction. A description thereof will be provided in more detail withreference to FIGS. 15 to 17B.

FIG. 15 is a block diagram illustrating an electronic apparatusaccording to an exemplary embodiment of the present invention. Referringto FIG. 15, the electronic apparatus 100 includes all or some of astoring unit 110, an input unit 120, an output unit 130, a curve guidingunit 140, an augmented reality providing unit 160, a controlling unit170, a communicating unit 180, a sensing unit 190, and a power supplyunit 195.

Here, the electronic apparatus 100 may be implemented as variousapparatuses such as a smartphone, a table computer, a notebook computer,a personal digital assistant (PDA), a portable multimedia player (PMP),a smart glass, a project glass, a navigation, a car dash cam or a carvideo recorder, which is an image photographing apparatus for a vehicle,capable of providing a driving related guidance to a driver of thevehicle, and may be included in the vehicle.

The driving related guidance may include a variety of guidance forassisting drivers of driving vehicles, such as a path guidance, a lanedeparture guidance, a lane keeping guidance, a front vehicle startingguidance, a traffic light change guidance, a front vehicle collisionprevention guidance, a road change guidance, a road guidance, a curveguidance, and the like.

Here, the path guidance may include an augmented reality path guidancethat performs the path guidance by incorporating a variety ofinformation such as a location, a direction, and the like of the user toan image obtained by photographing a front of the vehicle which is beingdriven, and a 2-dimensional (2D) or 3-dimensional (3D) path guidancethat performs the path guidance by incorporating a variety ofinformation such as the location, the direction, and the like of theuser to 2D or 3D map data.

As well, the path guidance may include an air map path guidance thatperforms the path guidance by incorporating a variety of informationsuch as the location, the direction, and the like of the user to air mapdata. Here, the path guidance may be construed as a concept includingthe path guidance when the user moves while walking or running, as wellas when the user drives the vehicle on board.

In addition, the lane departure guidance refers to guiding whether ornot the vehicle which is being driven departs from the lane.

In addition, the lane keeping guidance refers to guiding the vehicle toreturn to a lane on which the vehicle is originally being driven.

In addition, the front vehicle starting guidance may refer to informingof whether or not a vehicle located in the front of a vehicle which wasstopped starts.

In addition, the traffic light change guidance may refer to informing ofwhether or not a signal of a traffic light located at the front of thevehicle which was stopped is changed. As one example, the traffic lightchange guidance may refer to informing of a case in which the trafficlight is changed from a state in which a red traffic light indicating astop signal is turned on to a blue traffic light indicating a startsignal.

In addition, the front vehicle collision prevention guidance may referto informing that a distance between one vehicle which was stopped ordriven and another vehicle located at the front thereof becomes within apredetermined distance, in order to prevent a collision with the frontvehicle when the distance between the two vehicles becomes within thepredetermined distance.

In addition, the road change guidance may refer to guiding a driver tochange from a road on which the vehicle is located to another road inorder to perform the path guidance up to the destination.

In addition, the road guidance may refer to guiding a driver to keep ona road on which the vehicle is currently located.

In addition, the curve guidance may refer to informing that a road onwhich the vehicle is to be driven after a predetermined time is a curve.

A driving related image such as a front image of the vehicle enablingthe provision of the variety of guidance described above may bephotographed by a camera held onto the vehicle or a camera of thesmartphone. Here, the camera may be formed integrally with theelectronic apparatus 100 held on the vehicle to photograph the front ofthe vehicle.

As another example, the camera may be installed on the vehicleseparately from the electronic apparatus 100 to photograph the front ofthe vehicle. In this case, the camera may be a separate imagephotographing apparatus for a vehicle held toward the front of thevehicle, and the electronic apparatus 100 may receive the photographedimage via wired/wireless communications with the image photographingapparatus for a vehicle held separately from the electronic apparatus100, or when a storage medium storing the photographed image of theimage photographing apparatus for a vehicle is inserted into theelectronic apparatus 100, the electronic apparatus 100 may receive thephotographed image.

Hereinafter, the electronic apparatus 100 according to an exemplaryembodiment of the present invention will be further described in moredetail in addition to the description above.

The storing unit 110 serves to store a variety of data and applicationsthat are required to operate the electronic apparatus 100. Specifically,the storing unit 110 may store the data that is required to operate theelectronic apparatus 100, for example, an operating system (OS), a pathsearch application, map data, and the like. In addition, the storingunit 110 may store the data generated by the operation of the electronicapparatus 100, for example, searched path data, a received image, andthe like.

The storing unit 110 may be implemented as an embedded type of storageelement such as a random access memory (RAM), a flash memory, a readonly memory (ROM), an erasable programmable ROM (EPROM), anelectronically erasable and programmable ROM (EEPROM), a register, ahard disk, a removable disk, a memory card, a universal subscriberidentity module (USIM), or the like, as well as a removable type ofstorage element such as a USB memory, or the like.

The input unit 120 serves to convert a physical input from the outsideof the electronic apparatus 100 into a specific electrical signal. Here,the input unit 120 may include all or some of a user input unit 121 anda microphone unit 123.

The user input unit 121 may receive a user input such as a touch, a pushoperation, or the like. Here, the user input unit 121 may be implementedusing at least one of a form of various buttons, a touch sensorreceiving a touch input, and a proximity sensor receiving an approachingmotion.

The microphone unit 123 may receive voice of the user and soundgenerated from inside and outside of a vehicle.

The output unit 130 is an apparatus that outputs the data of theelectronic apparatus 100 to the user as the image and/or the voice.Here, the output unit 130 may include all or some of a display unit 131and an audio output unit 133.

The display unit 131 is an apparatus that outputs the data which may bevisually cognizable to the user. The display unit 131 may be implementedas the display unit provided to a front surface of a housing of theelectronic apparatus 100. In addition, the display unit 131 may beformed integrally with the electronic apparatus 100 to output visualrecognition data, and may also be installed separately from theelectronic apparatus 100 such as a head up display (HUD) to output thevisual recognition data.

The audio output unit 133 is an apparatus that outputs data which may beacoustically recognized by the electronic apparatus 100. The audiooutput unit 133 may be implemented as a speaker that represents data tobe informed to the user of the electronic apparatus 100 as sound.

The curve guiding unit 140 may perform the function of the curveguidance apparatus 10 as described above. Specifically, the curveguiding unit 140 may obtain link information corresponding to a road onwhich a vehicle is being driven, may determine a position of the vehicleon a link at a future time point, and judge a degree of risk of a curvesection in which the vehicle is to be driven after a predetermined timeusing the determined position of the vehicle and speed of the vehicle ata reference time point.

The augmented reality providing unit 160 may provide an augmentedreality view mode. Here, an augmented reality may be a method ofvisually overlapping additional information (e.g., a graphic elementrepresenting a point of interest (POI), a graphic element guiding acurve, a variety of additional information for assisting a safe drivingof a driver, and the like) on a screen displaying a real time imagewhich is being viewed by the user to provide the overlapped screen.

Further, this augmented reality providing unit 160 may include all orsome of a calibration unit, a 3D space generating unit, an objectgenerating unit, and a mapping unit.

The calibration unit may perform a calibration for estimating a cameraparameter corresponding to the camera from the photographed imagephotographed by the camera. Here, the camera parameter, which is aparameter including a camera matrix, which is information representing arelationship that an actual image is focused on a photograph, mayinclude camera extrinsic parameters and camera intrinsic parameters.

The 3D space generating unit may generate a virtual 3D space based onthe photographed image by the camera. Specifically, the 3D spacegenerating unit may generate the virtual 3D space by applying the cameraparameter estimated by the calibration unit to a 2D photographed image.

The object generating unit may generate an object for guidance on theaugmented reality, for example, a path guidance object, a road changeguidance object, a lane departure guidance object, a curve guidanceobject, and the like.

The mapping unit may map the object generated by the object generatingunit to the virtual 3D space generated by the 3D space generating unit.Specifically, the mapping unit may determine a position in the virtual3D space of the object generated by the object generating unit, and mayperform the mapping of the object to the determined position.

Furthermore, the communicating unit 180 may be provided so that theelectronic apparatus 100 communicates with other devices. Thecommunicating unit 180 may include all or some of a position data unit181, a wireless internet unit 183, a broadcast transmitting andreceiving unit 185, a mobile communicating unit 186, a local areanetwork communicating unit 187, and a wired communicating unit 189.

The position data unit 181 is an apparatus that obtains position datathrough a global navigation satellite system (GNSS). The GNSS means anavigation system capable of calculating a position of a receivingterminal using a radio signal received from a satellite. Detailedexamples of the GNSS may include a global positioning system (GPS),Galileo, a global orbiting navigational satellite system (GLONASS),COMPASS, an Indian regional navigational satellite system (IRNSS), aquasi-zenith satellite system (QZSS), and the like, depending on anoperator thereof. The position data unit 181 of the electronic apparatus100 according to an exemplary embodiment of the present invention mayobtain position data by receiving a GNSS signal serviced in an area inwhich the electronic apparatus 100 is used. Alternatively, the positiondata unit 181 may also obtain the position data through communicationswith a base station or an access point (AP) other than the GNSS.

The wireless internet unit 183 is an apparatus connected to the wirelessInternet to obtain or transmit data. The wireless internet unit 183 maybe connected to an Internet network through various communicationprotocols defined so as to perform transmission and reception ofwireless data of wireless the LAN (WLAN), wireless broadband (Wibro),world interoperability for microwave access (Wimax), and high speeddownlink packet access (HSDPA).

The broadcast transmitting and receiving unit 185 is an apparatus thattransmits and receives a broadcast signal through a variety of broadcastsystems. Examples of the broadcast systems which may performtransmission and reception through the broadcast transmitting andreceiving unit 185 may include the digital multimedia broadcastingterrestrial (DMBT), digital multimedia broadcasting satellite (DMBS),media forward link only (MediaFLO), digital video broadcast handheld(DVB-H), integrated services digital broadcast-terrestrial (ISDBT), andthe like. The broadcast signals transmitted and received through thebroadcast transmitting and receiving unit 185 may include traffic data,living data, and the like.

The mobile communicating unit 186 may be connected to a mobilecommunication network according to various mobile communicationstandards such as 3rd generation (3G), 3rd generation partnershipproject (3GPP), Long Term Evolution (LTE), and the like to perform voiceand data communications.

The local area network communicating unit 187 is an apparatus for localarea communications. The local area network communicating unit 187 maycommunicate through Bluetooth, radio frequency identification (RFID),infrared data association (IrDA), ultra wideband (UWB), ZigBee, nearfield communication (NFC), wireless-fidelity (WiFi), or the like, asdescribed above.

The wired communicating unit 189 is an interface apparatus capable ofconnecting the electronic apparatus 100 to other devices by wire. Thewired communicating unit 189 may be a USB module capable of performingcommunication through a USB port.

Further, the communicating unit 180 may communicate with other devicesusing at least one of the position data unit 181, the wireless internetunit 183, the broadcast transmitting and receiving unit 185, the mobilecommunicating unit 186, the local area network communicating unit 187,and the wired communicating unit 189.

As an example, in the case in which the electronic apparatus 100 doesnot include a camera function, the communicating unit 180 may receive animage photographed by the image photographing apparatus for a vehiclesuch as a car dash cam or a car video recorder, using at least one ofthe local area network communicating unit 187 and the wiredcommunicating unit 189.

As another example, in the case in which the communicating unit 180communicates with a plurality of devices, it can communicate with anyone of the plurality of devices through the local area networkcommunicating unit 187, and with another of the plurality of devicesthrough the wired communicating unit 189.

The sensing unit 190 is an apparatus capable of sensing a current stateof the electronic apparatus 100. The sensing unit 190 may include all orsome of a motion sensing unit 191 and a light sensing unit 193.

The motion sensing unit 191 may sense a motion of the electronicapparatus 100 on a 3 dimensional space. The motion sensing unit 191 mayinclude a tri-axis geomagnetic sensor and a tri-axis accelerationsensor. A more accurate trajectory of the vehicle to which theelectronic apparatus 100 is attached may be computed by incorporatingkinetic data obtained by the motion sensing unit 191 to the positiondata obtained by the position data unit 181.

The light sensing unit 193 is an apparatus that measures illuminancearound the electronic apparatus 100. A brightness of the display unit131 may be changed so as to correspond to an ambient brightness, usingilluminance data obtained by the light sensing unit 193.

The power supply unit 195 is an apparatus that supplies power requiredto operate the electronic apparatus 100 or operate other devicesconnected to the electronic apparatus 100. The power supply unit 195 maybe an apparatus that receives power from a battery embedded in theelectronic apparatus 100 or an external power supply such as a vehicle.In addition, the power supply unit 195 may be implemented as a wiredcommunicating module 119, or may also be implemented as an apparatusthat wirelessly receives the power, depending on a form receiving thepower.

The controlling unit 170 may control a general operation of theelectronic apparatus 100. Specifically, the controlling unit 170 maycontrol all or some of the storing unit 110, the input unit 120, theoutput unit 130, the curve guiding unit 140, the augmented realityproviding unit 160, the communicating unit 180, the sensing unit 190,and the power supply unit 195.

In particular, the controlling unit 170 may obtain link informationcorresponding to the road on which the vehicle is to be driven later.Here, the link information may be obtained from path guidance data forpath guidance up to a destination.

As an example, if destination information is input through the inputunit 120, the controlling unit 170 may generate the path guidance dataup to the destination using the map data which is pre-stored in thestoring unit 110. Alternatively, if the destination information is inputthrough the input unit 120, the controlling unit 170 may transmit a pathguidance request including at least one of current position informationand the destination information to a server. In addition, thecontrolling unit 170 may receive the path guidance data from the serveraccording to the path guidance request. In this case, the controllingunit 170 may obtain the link information corresponding to the road onwhich the vehicle is being driven from the path guidance data.

In addition, if driving prediction path information of the vehicle isgenerated based on real-time position information of the vehicle, thecontrolling unit 170 may obtain the link information based on theobtained driving prediction path information.

Meanwhile, the controlling unit 170 may determine a position of thevehicle on the link after predetermined time from the reference timepoint, and may judge whether or not the road on which the vehicle is tobe driven after the predetermined time is a dangerous curve in a case inwhich the vehicle is driven at current speed, using the determinedposition and speed of the vehicle at the reference time point. In thiscase, the controlling unit 170 may use the judgment processes of FIGS. 1to 7.

In addition, the controlling unit 170 may control the output unit 130 soas to output the curve guidance according to the judgment result. If adegree of risk of a curve is a first risk level, the controlling unit170 may control the output unit 130 so as to output a first curvesection guidance. Here, the first risk level may be a numerical valuerepresenting that the curve section is a curve requiring user attention.

If the degree of risk of the curve is a second risk level, thecontrolling unit 170 may control the output unit 130 so as to output asecond curve section guidance. Here, the second risk level may be anumerical value representing that the curve section is a curve requiringa higher attention (warning) of the user.

If the degree of risk of the curve is lower than the first risk level,the controlling unit 170 may control the output unit 130 so as not tooutput the curve guidance.

In addition, the controlling unit 170 may classify the degree of risk ofthe curve into three or more steps to thereby provide the curve riskguidance suitable for a situation for each of the steps to the user.

Further, the curve guidance may be performed within an augmented realityscreen. Specifically, the augmented reality providing unit 160 maygenerate a curve guidance object and map the generated curve guidanceobject to the virtual 3D space to thereby generate the augmented realityscreen, and the controlling unit 170 may control the display unit 131 soas to display the generated augmented reality screen.

FIG. 16 is a view illustrating a system network connected to theelectronic apparatus according to an exemplary embodiment of the presentinvention. Referring to FIG. 16, the electronic apparatus 100 accordingto an exemplary embodiment of the present invention may be implementedas a variety of apparatuses included in the vehicle such as anavigation, an image photographing apparatus for a vehicle, asmartphone, other augmented reality interface providing apparatuses fora vehicle, and the like, and may be connected to various communicationnetworks and other electronic devices 61 to 64.

In addition, the electronic apparatus 100 may be interworked with theGPS module according to radio signals received from satellites 20 tocompute a current position thereof and a current time zone thereof.

The respective satellites 20 may transmit L-band frequencies havingdifferent bands. The electronic apparatus 100 may compute the currentposition thereof based on a time that the L-band frequencies transmittedfrom the respective satellites 20 take to arrive at the electronicapparatus 100.

Meanwhile, the electronic apparatus 100 may be wirelessly connected to acontroller station 40 (ACR) through the communicating unit 180 and to anetwork (30) through a base station 50 (RAS), an access point (AP), orthe like. When the electronic apparatus 100 is connected to the network30, the electronic apparatus 100 may be indirectly connected to otherelectronic devices 61 and 62 connected to the network 30 to exchangedata with other electronic devices 61 and 62.

Meanwhile, the electronic apparatus 100 may also be indirectly connectedto the network 30 through another device 63 having a communicationfunction. For example, in the case in which the electronic apparatus 100does not include a module capable of being connected to the network 30,the electronic apparatus 100 may communicate with another device 63having the communication function through a local area networkcommunication module, or the like.

FIGS. 17A and 17B are views illustrating a curve guidance screen of theelectronic apparatus according to an exemplary embodiment of the presentinvention. FIG. 17A is a view illustrating a curve section guidancescreen in a case in which the degree of risk of a curve is the firstrisk level. Referring to FIG. 17A, the electronic apparatus 100 maygenerate first curve section guidance objects 1001 and 1003 representingthe degree of risk of the first risk level, and may output the generatedfirst curve section guidance objects 1001 and 1003 through the augmentedreality.

Meanwhile, FIG. 17B is a view illustrating a curve section guidancescreen in a case in which the degree of risk of a curve is the secondrisk level. Referring to FIG. 17B, the electronic apparatus 100 maygenerate second curve section guidance objects 1002 and 1004representing the degree of risk of the second risk level, and may outputthe generated second curve section guidance objects 1002 and 1004through the augmented reality.

Here, the first curve section guidance objects 1001 and 1003 may be theobjects informing that the curve section is a curve requiring userattention. That is, the first curve section guidance may be attentionguidance for informing a risk that the vehicle deviates from the road ofthe curve section when the vehicle passes through the curve section.

The second curve section guidance objects 1002 and 1004 may be theobjects informing that the curve section is a curve requiring a higherattention of the user. That is, the second curve section guidance may bea warning guidance for informing a turnover risk of the vehicle thatwill pass through the curve section.

Therefore, the first curve section guidance objects 1001 and 1003 andthe second curve section guidance objects 1002 and 1004 may beimplemented so as to be distinguished from each other by differentshapes, colors, or the like.

Meanwhile, the first curve section guidance objects 1001 and 1003 andthe second curve section guidance objects 1002 and 1004 may be displayedalong an area on which a self-vehicle is driven among road areas of theaugmented reality screen. In addition, the first curve section guidanceobjects 1001 and 1003 and the second curve section guidance objects 1002and 1004 may be implemented by a texture image to be displayed throughthe augmented reality. Accordingly, the driver may easily recognize theroad on which the self-vehicle is being driven.

In addition, the electronic apparatus 100 may also output the firstcurve section guidance objects 1001 and 1003 and the second curvesection guidance objects 1002 and 1004 through voice.

FIG. 18 is a flowchart illustrating a curve guidance method of anelectronic apparatus according to an exemplary embodiment of the presentinvention. Referring to FIG. 18, first, the electronic apparatus 100 mayobtain link information corresponding to a road on which a vehicle is tobe driven later (S501). Here, the link information may be obtained frompath guidance data for path guidance up to a destination. Alternatively,the link information may be obtained based on information on predictionpath on which a driving of the vehicle is predicted.

In addition, the electronic apparatus 100 may determine a position ofthe vehicle on the link at a current time point and a future time point(S502).

In addition, the electronic apparatus 100 may judge the degree of riskof the curve section in which the vehicle is to be driven after apredetermined time when the vehicle drives at current speed, using thedetermined position at the future time point and speed of the vehicle ata reference time point, which is the current time point (S503). In thiscase, the controlling unit 170 may use the judgment processes of FIGS. 1to 14.

If the degree of risk of a curve is the first risk level, the electronicapparatus 100 may output the first curve section guidance (S504).

If the degree of risk of the curve is the second risk level, theelectronic apparatus 100 may output the second curve section guidance(S505).

If the degree of risk of the curve is lower than the first risk level,the electronic apparatus 100 may not output the curve section guidance(S506).

FIG. 19 is a view illustrating an embodiment where an electronicapparatus does not include a photographing unit. Referring to FIG. 19,an image photographing apparatus 200 for a vehicle which is providedseparately from the electronic apparatus 100 for a vehicle may configurea system according to an exemplary embodiment of the present inventionusing a wired/wireless communication scheme.

The electronic apparatus 100 for a vehicle may include a display unit131, a user input unit 121, and a microphone unit 123 which are providedto a front of a housing 191.

The image photographing apparatus 200 for a vehicle may include a camera222, a microphone 224, and an attaching unit 281.

FIG. 20 is a view illustrating an embodiment where the electronicapparatus includes the photographing unit. Referring to FIG. 20, whenthe electronic apparatus 100 includes the photographing unit 150, theelectronic apparatus 100 may be an apparatus in which the photographingunit 150 of the electronic apparatus 100 photographs a front of thevehicle and a display portion of the electronic apparatus 100 may berecognized by the user. Accordingly, a system according to an exemplaryembodiment of the present invention may be implemented.

FIG. 21 is a view illustrating an embodiment using a head-up display(HUD). Referring to FIG. 21, the HUD may display the augmented realityguidance screen on the head-up display through wired/wirelesscommunications with other devices.

As an example, the augmented reality may be provided through the HUDusing a front window of the vehicle or an image overlay using a separateimage output apparatus, and the augmented reality providing unit 160 maygenerate an interface image or the like which overlays a reality imageor a window. Thereby, an augmented reality navigation or a vehicleinfotainment system may be implemented.

Furthermore, the curve guidance method according to various exemplaryembodiments of the present invention described above may be implementedin a program so as to be provided to the server or devices. Accordingly,the respective apparatuses may be connected to the server or the devicein which the program is stored to download the program.

In addition, the control method according to various exemplaryembodiments of the present invention described above may be implementedin the program and be provided to be stored in various non-transitorycomputer-readable medium. The non-transitory computer-readable mediumdoes not mean a medium storing data for a short period such as aregister, a cache, a memory, or the like, but means a medium whichsemi-permanently stores the data and is readable by a machine.Specifically, various applications or programs described above may beprovided to be stored in the non-transitory computer readable mediumsuch as a compact disc (CD), a digital versatile disk (DVD), a harddisk, a Blu-ray disk, a universal serial bus (USB), a memory card, aread-only memory (ROM), or the like.

As described above, according to various exemplary embodiments of thepresent invention, since whether or not the road on which the vehicle isto be driven after the predetermined time is the curve section may bejudged in real time using existing retained link information, the curveguidance may be performed without needing the pre-survey for the curvesections across the country, which incurs high cost.

As well, when the degree of risk for the curve section in which thevehicle is to be driven after the predetermined time is guided, sincethe guidance that a curvature of the curve section and current drivingspeed of the vehicle are simultaneously considered is provided, the usermay more effectively cope with the curve section. As an example, in acase in which because the curvature of the curve section is large, butthe vehicle is currently driven at low speed, the vehicle has lowpossibility that it will be exposed to a risk in the curve section, thedegree of risk is not guided, which prevents the driving of the userfrom being disturbed due to an unnecessary guidance, thereby making itpossible to improve safety of the user.

Further, according to various exemplary embodiments of the presentinvention, whether or not the degree of risk is guided is controlled byreflecting factors capable of influencing the degree of risk of thecurve section which is felt by a sensory organ of the user, for example,a road rank (e.g., information on whether the road is a highway or ageneral road), a road width (e.g., information on whether a road widthis wide or narrow, or road width information), the number of lanes ofthe road (e.g., information on whether the number of lanes of the roadis large or small, or information of the number of lanes of the road), aroad slope (e.g., whether the road is an uphill road or a downhill road,or superelevation information), thereby making it possible to moreaccurately perform the guidance for the degree of risk of the curvesection.

Further, according various exemplary embodiments of the presentinvention, since the degree of risk of the curve section is divided intotwo or more steps and is guided to the user, the user may recognize thedegree of risk according to a situation in the curve section for each ofthe steps, thereby making it possible to more effectively cope with thecurve section.

Hereinabove, although the exemplary embodiments of the present inventionhave been shown and described, it should be understood that the presentinvention is not limited to the disclosed embodiments and may bevariously changed without departing from the spirit and the scope of thepresent invention. Therefore, the present invention should be construedas including all the changes, equivalents, and substitutions included inthe spirit and scope of the present invention.

What is claimed is:
 1. A curve guidance method comprising: obtaininglink information corresponding to a road including a plurality of links;determining at least one position of a vehicle on at least one of theplurality of links at at least one future time point based on theobtained link information; and judging a degree of risk of a curvesection of the road in which the vehicle is to be driven after apredetermined time using the determined at least one position and aspeed of the vehicle at a reference time point which corresponds to acurrent position of the vehicle.
 2. The curve guidance method of claim1, wherein the determining of the at least one position of the vehiclecomprises respectively determining a plurality of positions of thevehicle on the plurality of links at each of a plurality of future timepoints, and the judging of the degree of risk of the curve sectioncomprises computing centrifugal force to be applied to the vehicle inthe curve section using the plurality of determined positions and thespeed of the vehicle at the reference time point, and judging the degreeof risk of the curve section based on the computed centrifugal force. 3.The curve guidance method of claim 2, wherein the determining of theplurality of positions of the vehicle includes: determining a firstposition corresponding to a position of the vehicle on a first link ofthe plurality of links at a first time point, which is after a firsttime from the reference time point; determining a second positioncorresponding to a position of the vehicle on a second link of theplurality of links at a second time point, which is after a second timefrom the reference time point; and determining a third positioncorresponding to a position of a point on the first link, the secondlink or a third link that is located between the first link and thesecond link, the third position being positioned farthest from a linesegment connecting the first position and the second position.
 4. Thecurve guidance method of claim 2, wherein the determining of theplurality of positions of the vehicle includes: determining a firstposition corresponding to a position of the vehicle on a first link ofthe plurality of links at a first time point, which is after a firsttime from the reference time point; determining a second positioncorresponding to a position of the vehicle on a second link of theplurality of links at a second time point, which is after a second timefrom the reference time point; and determining a third positioncorresponding to a position of at least one point on the first link, thesecond link or a third link that is located between the first link andthe second link, the third position being positioned between the firstposition and the second position.
 5. The curve guidance method of claim3, wherein the judging of the degree of risk of the curve sectionincludes generating a circumscribed circle including the first position,the second position, and the third position.
 6. The curve guidancemethod of claim 2, wherein, in the judging of the degree of risk of thecurve section, the degree of risk of the curve section in which thevehicle is to be driven is judged by comparing the computed centrifugalforce with a preset threshold value.
 7. The curve guidance method ofclaim 6, wherein the preset threshold value includes a first thresholdvalue, which is a judgment reference of a first risk level, and a secondthreshold value, which is a judgment reference of a second risk levelhaving the degree of risk higher than that of the first risk level. 8.The curve guidance method of claim 7, wherein the obtaining of the linkinformation comprises obtaining link attribute information, wherein thelink information and the attribute information are obtained from mapdata, and wherein the link attribute information includes at least oneof identifier of the road, a start point and an end point of a referencelink of a moving direction of the vehicle, a road number, a road name, aroad length, road rank information, road width information, informationof the number of lanes of the road, and road slope information.
 9. Thecurve guidance method of claim 8, further comprising: computing a weightfor adjusting the first threshold value and the second threshold valuebased on the link attribute information; and adjusting the firstthreshold value and the second threshold value based on the computedweight.
 10. A curve guidance apparatus comprising: a link informationobtaining unit obtaining link information corresponding to a roadincluding a plurality of links; a speed sensing unit sensing speed of avehicle; a link position determining unit determining at least oneposition of the vehicle on at least one of the plurality of links at atleast one future time point from a reference time point whichcorresponds to a current position of the vehicle based on the obtainedlink information; and a controlling unit judging a degree of risk of acurve section of the road in which the vehicle is to be driven after apredetermined time using the determined at least one position and aspeed of the vehicle at the reference time point.
 11. The curve guidanceapparatus of claim 10, wherein the link position determining unitrespectively determines a plurality of positions of the vehicle on theplurality of links at each of a plurality of future time points, and thecontrolling unit includes: a centrifugal force computing unit computingcentrifugal force to be applied to the vehicle in the curve sectionusing the plurality of determined positions and the speed of the vehicleof the reference time point; and a degree of risk judging unit judgingthe degree of risk of the curve section based on the computedcentrifugal force.
 12. The curve guidance apparatus of claim 11, whereinthe link position determining unit includes: a first link positiondetermining unit determining a first position corresponding to aposition of the vehicle on a first link of the plurality of links at afirst time point, which is after a first time from the reference timepoint; a second link position determining unit determining a secondposition corresponding to a position of the vehicle on a second link ofthe plurality of links at a second time point, which is after a secondtime from the reference time point; and a third link positiondetermining unit determining a third position corresponding to aposition of a point on the first, the second link or a third link thatis located between the first link and the second link, the thirdposition being positioned farthest from a line segment connecting thefirst position and the second position.
 13. The curve guidance apparatusof claim 11, wherein the link position determining unit includes: afirst link position determining unit determining a first positioncorresponding to a position of the vehicle on a first link of theplurality of links at a first time point, which is after a first timefrom the reference time point; a second link position determining unitdetermining a second position corresponding to a position of the vehicleon a second link of the plurality of links at a second time point, whichis after a second time from the reference time point; and a third linkposition determining unit determining a third position corresponding toa position of at least one point on the first link, the second link or athird link that is located between the first link and the second link,the third position being positioned between the first position and thesecond position.
 14. The curve guidance apparatus of claim 12, whereinthe controlling unit includes a circumscribed circle generating unitgenerating a circumscribed circle including the first position, thesecond position, and the third position.
 15. The curve guidanceapparatus of claim 14, wherein the centrifugal force computing unitcomputes the centrifugal force using a radius of the generatedcircumscribed circle and the speed of the vehicle at the reference timepoint.
 16. The curve guidance apparatus of claim 11, wherein the degreeof risk judging unit judges the degree of risk of the curve section inwhich the vehicle is to be driven by comparing the computed centrifugalforce with a preset threshold value.
 17. The curve guidance apparatus ofclaim 16, wherein the preset threshold value includes a first thresholdvalue, which is a judgment reference of a first risk level, and a secondthreshold value, which is a judgment reference of a second risk levelhaving the degree of risk higher than that of the first risk level. 18.The curve guidance apparatus of claim 17, wherein the link informationobtaining unit further obtains link attribute information correspondingto the road, wherein the link information and the attribute informationare obtained from map data, and wherein the link attribute informationincludes at least one of identifier of the road, a start point and anend point of a reference link of a moving direction of the vehicle, aroad number, a road name, a road length, road rank information, roadwidth information, information of the number of lanes of the road, androad slope information.
 19. The curve guidance apparatus of claim 18,wherein the controlling unit further includes a weight computing unitcomputing a weight for adjusting the first threshold value and thesecond threshold value based on the link attribute information, andadjusting the first threshold value and the second threshold value basedon the computed weight.
 20. The curve guidance apparatus of claim 12,wherein, when the vehicle enters the curve section, the first linkposition determining unit determines the first position by shorteningthe first time.